# List of state routes in Connecticut

The Connecticut Department of Transportation (CTDOT) maintains a system of state highways to serve the predominant flow of traffic between towns within Connecticut, and to towns in surrounding states. State highways also include roads that provide access to federal and state facilities (Special Service Roads).
The state highway system consists of roads indicated on the official CTDOT map and highway log. As of January 1, 2007, the state highway system contains a total of 3,719 miles (5,985 km) of roads (not including ramps and interchange connections), corresponding to approximately 20% of all roads in the state. All state highways are state-maintained except for several segments (totaling 4 miles) that are locally maintained. Interstate highways and U.S. highways in the state are not Connecticut state routes, however they are maintained by the state.
All state highways are given a number designation. All state highways are assigned Route numbers. Route numbers are in the 2–999 range. State highways that are special service roads are assigned SSR numbers and are unsigned; these numbers are above 399 and are used for internal CTDOT purposes. Signposted state highways that are not U.S. highways or interstates are signed with the square Connecticut state highway shield.

## State Routes

Routes are signed state highways and are assigned numbers from 1 to 399 (with the exception of I-684 and I-691). All state, U.S. and Interstate highways are part of the same numbering system. In 1926, the U.S. highway system was implemented. U.S. Routes 1, 5, 6, and 7 were used as designations on several primary state highways, replacing New England routes 1, 2, 3, and 4, respectively. The other New England routes that were not re-designated as U.S. routes became ordinary state highways but kept their number designation, which are used even today (with some realignment). In 1958, Connecticut received approval for the route numbers of its three primary Interstate highways: I-84, I-91, and I-95. State highways with the same number designation as the Interstate highways were renumbered to avoid duplication of route numbers.
| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| Route 2 | 58.03 | 93.39 | Columbus Boulevard/State Street in Hartford | US 1 in Stonington | 01932-01-011932 | current | |
| Route 2A | 9.91 | 15.95 | I-395/Route 2/Route 32 in Norwich | Route 2 in Preston | 01967-01-011967 | current | |
| Route 3 | 14.48 | 23.30 | Route 66 in Middletown | Route 2 in East Hartford | 01941-01-011941 | current | Extended in 1991 |
| Route 4 | 46.72 | 75.19 | Route 41/Route 343 in Sharon | Farmington Avenue in West Hartford | 01932-01-011932 | current | |
| Route 8 | 67.36 | 108.41 | I-95 in Bridgeport | Route 8 at the Massachusetts state line | 01922-01-011922 | current | Rerouted in 1951 |
| Route 8A | 1.31 | 2.11 | US 1 in Stratford | Route 8 in Stratford | 01932-01-011932 | 01951-01-011951 | Now Route 110 |
| Route 9 | 40.89 | 65.81 | I-95/US 1 in Old Saybrook | I-84/US 6 in Farmington | 01932-01-011932 | current | |
| Route 9A | 15.4 | 24.8 | Route 9 in Essex | Route 9 in Middletown | 01968-01-011968 | 01986-01-011986 | Now Route 154 |
| Route 10 | 54.28 | 87.36 | I-95 in New Haven | US 202/Route 10 at the Massachusetts state line | 01922-01-011922 | current | |
| Route 10A | 3.62 | 5.83 | Whitney Avenue in New Haven | Route 10 in Hamden | 01932-01-011932 | 01970-01-011970 | |
| Route 11 | 7.42 | 11.94 | Route 82 in Salem | Route 2 in Colchester | 01971-07-011971 | current | Length includes only completed portion |
| Route 12 | 54.46 | 87.64 | I-95/US 1/Route 184 in Groton | Route 12 at the Massachusetts state line | 01922-01-011922 | current | |
| Route 14 | 24.33 | 39.16 | Route 66/Route 195 in Windham | Route 14 at the Rhode Island state line | 01932-01-011932 | current | |
| Route 14A | 10.27 | 16.53 | Route 14 in Plainfield | Route 14 in Sterling | 01963-01-011963 | current | |
| Route 15 | 83.53 | 134.43 | Hutchinson River Parkway at the New York state line | I-84/US 6 in East Hartford | 01932-01-011932 | current | Includes Merritt Parkway, Wilbur Cross Parkway, Berlin Turnpike, and Wilbur Cross Highway; relocated in 1948 |
| Route 15A | 3.02 | 4.86 | US 6A/Route 15 in Portland | Route 15 in Portland | 01932-01-011932 | 01948-01-011948 | Now Route 17A |
| Route 16 | 17.05 | 27.44 | Route 66 in East Hampton | Route 207 in Lebanon | 01934-01-011934 | current | Extended in 1963 |
| Route 16A | — | — | — | — | 01942-01-011942 | 01963-01-011963 | ㅤ |
| Route 17 | 36.41 | 58.60 | I-91/Route 80/Middletown Avenue in New Haven | Route 2 in Glastonbury | 01948-01-011948 | current | |
| Route 17A | 3.02 | 4.86 | Route 17/Route 66 in Portland | Route 17 in Portland | 01948-01-011948 | current | |
| Route 18 | 2.23 | 3.59 | Route 72 in Cromwell | Route 9 in Cromwell | 01940-01-011940 | 01951-01-011951 | Now Route 372 |
| Route 19 | 6.99 | 11.25 | Route 190 in Stafford | Route 19 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 20 | 31.56 | 50.79 | Route 8 in Winchester | I-91 in Windsor Locks | 01932-01-011932 | current | Includes part of Bradley Airport Connector |
| Route 21 | 5.67 | 9.12 | Route 12 in Killingly | Route 193 in Thompson | 01944-01-011944 | current | |
| Route 22 | 14.07 | 22.64 | Route 10/Route 40 in Hamden | US 1 in Guilford | 01951-01-011951 | current | |
| Route 25 | 28.59 | 46.01 | I-95 in Bridgeport | US 202 in Brookfield | 01932-01-011932 | current | |
| Route 25A | — | — | — | — | 01932-01-011932 | 01933-01-011933 | Now part of Route 25 |
| Route 27 | 3.21 | 5.17 | US 1 in Stonington | Route 184 in Groton | 01950-01-011950 | current | |
| Route 29 | 9.41 | 15.14 | US 1 in Darien | Westchester Avenue at the New York state line | 01932-01-011932 | 01966-01-011966 | Renumbered Route 124 to match New York |
| Route 30 | 20.94 | 33.70 | I-291/US 5 in South Windsor | Route 190 in Stafford | 01943-01-011943 | current | |
| Route 31 | 14.34 | 23.08 | Route 32 in Mansfield | Route 74 in Vernon | 01942-01-011942 | current | Extended in 1963 |
| Route 32 | 54.88 | 88.32 | I-95/US 1/Eugene O'Neill Drive in New London | Route 32 at the Massachusetts state line | 01922-01-011922 | current | Realigned in 1932 |
| Route 33 | 14.41 | 23.19 | I-95/Route 136 in Westport | Route 35 in Ridgefield | 01932-01-011932 | current | |
| Route 34 | 21.88 | 35.21 | Washington Avenue in Newtown | Route 10 in New Haven | 01932-01-011932 | current | Removed from the Oak Street Connector in 2023 |
| Route 35 | 5.66 | 9.11 | NY 35 at the New York state line | US 7 in Ridgefield | 01932-01-011932 | current | |
| Route 35A | 1.02 | 1.64 | West Lane at the New York state line | Route 35 in Ridgefield | 01933-01-011933 | 01963-01-011963 | Replaced by unsigned SR 835 |
| Route 37 | 18.66 | 30.03 | I-84/US 6/US 7/US 202/Route 39/Route 53 in Danbury | US 7 in New Milford | 01932-01-011932 | current | |
| Route 39 | 22.76 | 36.63 | I-84/US 6/US 7/US 202/Route 37/Route 53 in Danbury | Route 55 in Sherman | 01932-01-011932 | current | |
| Route 40 | 3.08 | 4.96 | I-91/Bailey Road in North Haven | Route 10/Route 22 in Hamden | 01976-01-011976 | current | |
| Route 41 | 17.86 | 28.74 | CR 2 at the New York state line | Route 41 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 42 | 13.66 | 21.98 | Route 67 in Oxford | Route 10 in Cheshire | 01963-01-011963 | current | |
| Route 43 | 5.06 | 8.14 | Route 4/Route 128 in Cornwall | Route 63 in Cornwall | 01932-01-011932 | current | |
| Route 45 | 10.29 | 16.56 | US 202 in Washington | US 7 in Cornwall | 01932-01-011932 | current | |
| Route 47 | 12.27 | 19.75 | US 6 in Woodbury | US 202 in Washington | 01932-01-011932 | current | |
| Route 49 | 17.96 | 28.90 | Route 4 in Torrington | Norfolk Road at the Massachusetts state line | 01932-01-011932 | 01954-01-011954 | Replaced by extended Route 72; this road became Route 272 in 1963 |
| Route 49 | 21.74 | 34.99 | Route 2 in Stonington | Route 14A in Sterling | 01959-01-011959 | current | |
| Route 51 | 9.4 | 15.1 | Route 156 in Old Lyme | I-95/US 1 in East Lyme | 01962-01-011962 | 01976-01-011976 | Former route of US 1, replaced by US 1 again when it was rerouted off of I-95 |
| Route 52 | 54.69 | 88.02 | I-95 in Waterford | Route 52 at the Massachusetts state line | 01964-01-011964 | 01983-01-011983 | Replaced by I-395 when it was rerouted off of I-95 |
| Route 53 | 23.57 | 37.93 | US 1 in Norwalk | I-84/US 6/US 7/US 202/Route 37/Route 39 in Danbury | 01932-01-011932 | current | |
| Route 55 | 2.64 | 4.25 | NY 55 at the New York state line | US 7 in New Milford | 01932-01-011932 | current | |
| Route 57 | 9.51 | 15.30 | Route 33 in Westport | US 7 in Georgetown | 01932-01-011932 | current | |
| Route 58 | 18.58 | 29.90 | US 1 in Fairfield | Route 302 in Bethel | 01932-01-011932 | current | |
| Route 58A | 1.23 | 1.98 | — | — | 01932-01-011932 | 01935-01-011935 | Renumbered US 202A in 1935 |
| Route 59 | 12.05 | 19.39 | US 1 in Bridgeport | Route 25 in Monroe | 01932-01-011932 | current | |
| Route 61 | 9.16 | 14.74 | US 6 in Woodbury | Route 63 in Morris | 01932-01-011932 | current | |
| Route 63 | 52.57 | 84.60 | Route 10 in New Haven | US 7 in Canaan | 01932-01-011932 | current | |
| Route 64 | 8.14 | 13.10 | US 6 in Woodbury | I-84 in Waterbury | 01932-01-011932 | current | |
| Route 65 | 9.66 | 15.55 | US 1 in Bridgeport | Route 8 in Shelton | 01932-01-011932 | 01951-01-011951 | Redesignated as part of a rerouted Route 8 in 1951 |
| Route 65A | 2.91 | 4.68 | Route 65 in Trumbull | Route 65 in Shelton | 01944-01-011944 | 01951-01-011951 | Now Route 108 |
| Route 66 | 38.38 | 61.77 | I-91/I-691 in Meriden | US 6 in Windham | 01968-01-011968 | current | |
| Route 67 | 31.00 | 49.89 | Route 63 in Woodbridge | US 7/US 202 in New Milford | 01932-01-011932 | current | |
| Route 67A | 1.20 | 1.93 | Route 133 in Bridgewater | Route 67 in Bridgewater | 01959-01-011959 | 01963-01-011963 | Replaced by unsigned SR 867 |
| Route 68 | 22.09 | 35.55 | Route 63 in Naugatuck | Route 17 in Durham | 01932-01-011932 | current | |
| Route 69 | 35.16 | 56.58 | Route 63 in New Haven | Route 4 in Burlington | 01932-01-011932 | current | |
| Route 70 | 10.92 | 17.57 | I-84 in Cheshire | Route 71 in Meriden | 01932-01-011932 | current | |
| Route 71 | 19.19 | 30.88 | US 5 in Wallingford | Route 173 in West Hartford | 01932-01-011932 | current | |
| Route 71A | 2.92 | 4.70 | Route 71 in Berlin | Kensington Avenue in New Britain | 01978-01-011978 | current | |
| Route 72 | 20.05 | 32.27 | Route 4 in Harwinton | Route 9/Route 71/Route 174 in New Britain | 01932-01-011932 | current | |
| Route 73 | 3.46 | 5.57 | Route 63 in Watertown | Route 8 in Waterbury | 01932-01-011932 | current | |
| Route 74 | 22.21 | 35.74 | Route 194 in South Windsor | US 44 in Ashford | 01932-01-011932 | current |
| Route 75 | 13.52 | 21.76 | Route 159/Route 305 in Windsor | Route 75 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 76 | — | — | — | — | — | 01951-01-011951 | |
| Route 77 | 13.85 | 22.29 | Route 146 in Guilford | Route 17 in Durham | 01932-01-011932 | current | |
| Route 78 | 0.43 | 0.69 | Route 2 in Stonington | Route 78 at the Rhode Island state line | 01979-01-011979 | current | |
| Route 79 | 14.34 | 23.08 | US 1 in Madison | Route 17 in Durham | 01932-01-011932 | current | |
| Route 80 | 25.91 | 41.70 | I-91/Route 17 in New Haven | Route 154 in Deep River | 01932-01-011932 | current | |
| Route 81 | 15.75 | 25.35 | US 1 in Clinton | Route 154 in Haddam | 01932-01-011932 | current | |
| Route 82 | 28.47 | 45.82 | Route 9 in Chester | Route 2/Route 32 in Norwich | 01932-01-011932 | current | |
| Route 83 | 27.56 | 44.35 | New London Turnpike in Glastonbury | Route 83 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 84 | — | — | — | — | — | 01959-01-011959 | Renumbered Route 95, and is now Route 184 because of I-84 |
| Route 85 | 37.38 | 60.16 | US 1 in New London | US 6/US 44 in Bolton | 01932-01-011932 | current | |
| Route 86 | — | — | — | — | — | 01951-01-011951 | Replaced by an extended Route 156 |
| Route 87 | 16.62 | 26.75 | Route 32 in Franklin | US 6 in Andover | 01932-01-011932 | current | |
| Route 89 | 16.25 | 26.15 | Route 195 in Mansfield | Route 190 in Union | 01932-01-011932 | current | |
| Route 91 | — | — | — | — | 01932-01-011932 | 01959-01-011959 | Renumbered Route 171 to avoid confusion with I-91 |
| Route 93 | — | — | — | — | 01932-01-011932 | 01959-01-011959 | |
| Route 94 | 9.33 | 15.02 | Route 2 in Glastonbury | Route 85 in Hebron | 01932-01-011932 | current | |
| Route 95 | — | — | — | — | 01932-01-011932 | 01959-01-011959 | Renumbered Route 49 because of I-95 |
| Route 95 | — | — | — | — | 01959-01-011959 | 01964-01-011964 | Renumbered Route 184 |
| Route 95A | — | — | — | — | — | 01959-01-011959 | Renumbered Route 14 |
| Route 97 | 29.14 | 46.90 | Route 12 in Norwich | US 44/Route 169 in Pomfret | 01932-01-011932 | current | |
| Route 99 | 10.64 | 17.12 | Route 9 in Cromwell | US 5/Route 15/Wethersfield Avenue in Wethersfield | 01969-01-011969 | current | |
| Route 100 | 4.40 | 7.08 | US 1 in East Haven | Route 80 in East Haven | 01935-01-011935 | current | |
| Route 101 | — | — | — | — | — | 01935-01-011935 | Replaced by US 44 |
| Route 101 | 9.46 | 15.22 | US 44 in Pomfret | Route 101 at the Rhode Island state line | 01935-01-011935 | current | |
| Route 102 | 3.45 | 5.55 | Route 35 in Ridgefield | US 7 in Ridgefield | 01932-01-011932 | current | |
| Route 103 | 5.31 | 8.55 | Route 80 in New Haven | US 5/Route 22 in North Haven | 01987-01-011987 | current | |
| Route 104 | 6.82 | 10.98 | Route 137 in Stamford | Long Ridge Road at the New York state line | 01935-01-011935 | current | |
| Route 105 | — | — | — | — | — | 01963-01-011963 | Now Route 190 |
| Route 106 | — | — | Route 58 near Easton | Route 59 near Easton | — | 01963-01-011963 | Center Street; decommissioned in exchange for creating the current Route 106 |
| Route 106 | 14.37 | 23.13 | I-95/US 1 in Stamford | Route 53 in Wilton | 01963-01-011963 | current | |
| Route 107 | 7.50 | 12.07 | US 7 in Georgetown | Route 58 in Redding | 01932-01-011932 | current | |
| Route 108 | 11.05 | 17.78 | US 1 in Stratford | Route 110 in Shelton | 01932-01-011932 | current | |
| Route 109 | 20.93 | 33.68 | US 202 in New Milford | US 6 in Thomaston | 01932-01-011932 | current | |
| Route 110 | 15.95 | 25.67 | I-95/US 1/Route 130 in Stratford | Route 111 in Monroe | 01935-01-011935 | current | Extended in 1952 |
| Route 111 | 11.71 | 18.85 | Route 15/Merritt Parkway in Trumbull | Route 34 in Monroe | 01932-01-011932 | current | |
| Route 112 | 6.68 | 10.75 | US 44 in Salisbury | US 7 in Salisbury | 01932-01-011932 | current | |
| Route 113 | 8.12 | 13.07 | I-95 at the Bridgeport–Stratford line | Route 110 in Stratford | 01932-01-011932 | current | |
| Route 114 | 7.92 | 12.75 | US 1 in Orange | Route 63 in Woodbridge | 01932-01-011932 | current | |
| Route 115 | 5.66 | 9.11 | Route 34 in Derby | Route 67 in Seymour | 01932-01-011932 | current | |
| Route 116 | — | — | — | — | 01932-01-011932 | 01967-01-011967 | Renumbered Route 118 so that Route 116 could be reused to match New York |
| Route 116 | 4.24 | 6.82 | Route 35 in Ridgefield | NY 116 at the New York state line | 01966-01-011966 | current | |
| Route 117 | 11.32 | 18.22 | US 1 in Groton | Route 2 in Preston | 01963-01-011963 | current | |
| Route 118 | — | — | — | — | — | 01962-01-011962 | |
| Route 118 | 7.48 | 12.04 | Route 63 in Litchfield | Route 4 in Harwinton | 01966-01-011966 | current | Route 116 designation from 1932-1967 |
| Route 119 | — | — | — | — | — | 01963-01-011963 | Now Route 201 |
| Route 120 | 3.11 | 5.01 | Route 322 in Southington | Route 10 in Southington | 01932-01-011932 | current | |
| NY 120A | 4.6 | 7.4 | NY 120A at the New York state line | NY 120A at the New York state line | 01931-01-011931 | current | King St, Greenwich ... parts in CT and other parts along NY/CT line |
| Route 121 | 5.66 | 9.11 | US 1 in Milford | Route 34 in Orange | 01932-01-011932 | current | |
| Route 122 | 3.51 | 5.65 | I-95 in West Haven | Route 63 in New Haven | 01932-01-011932 | current | |
| Route 123 | 8.37 | 13.47 | US 1 in Norwalk | NY 123 at the New York state line | 01932-01-011932 | current | realigned in 1934 |
| Route 124 | — | — | — | — | — | 01963-01-011963 | Demoted to SR 832 and SR 834 |
| Route 124 | 9.41 | 15.14 | US 1 in Darien | Westchester Avenue at the New York state line | 01966-01-011966 | current | |
| Route 125 | 1.24 | 2.00 | Route 4 in Cornwall | Route 128 in Cornwall | 01932-01-011932 | current | |
| Route 126 | 6.08 | 9.78 | Route 63 in Canaan | US 44 in North Canaan | 01932-01-011932 | current | |
| Route 127 | 6.80 | 10.94 | I-95/Route 130 in Bridgeport | Route 111 in Trumbull | 01932-01-011932 | current | |
| Route 128 | 4.03 | 6.49 | US 7 in Sharon | Route 4/Route 43 in Cornwall | 01932-01-011932 | current | |
| Route 129 | — | — | — | — | — | 01963-01-011963 | Now Route 130 |
| Route 130 | 8.21 | 13.21 | US 1 in Fairfield | I-95/US 1/Route 110 in Stratford | 01992-01-011992 | current | |
| Route 131 | — | — | — | — | — | 01935-01-011935 | Renumbered Route 199 so that Route 131 could be used to match Massachusetts |
| Route 131 | 3.78 | 6.08 | Route 12 in Thompson | Route 131 at the Massachusetts state line | 01935-01-011935 | current | |
| Route 132 | 10.97 | 17.65 | Route 47 in Woodbury | Route 63 in Watertown | 01932-01-011932 | current | |
| Route 133 | 20.05 | 32.27 | US 202 in Brookfield | Route 67 in Bridgewater | 01932-01-011932 | current | |
| Route 134 | — | — | — | — | — | 01963-01-011963 | Decommissioned in 1956, but restored in 1961; replaced by rerouted Route 109 |
| Route 135 | 2.58 | 4.15 | I-95/US 1 in Fairfield | Route 58 in Fairfield | 01953-01-011953 | current | |
| Route 136 | 20.46 | 32.93 | US 1 in Darien | Route 59 in Easton | 01932-01-011932 | current | |
| Route 137 | 9.33 | 15.02 | US 1 in Stamford | NY 137 at the New York state line | 01932-01-011932 | current | |
| Route 138 | 17.73 | 28.53 | Route 97 in Sprague | Route 138 at the Rhode Island state line | 01932-01-011932 | current | |
| Route 139 | 2.38 | 3.83 | US 1 in Branford | Route 22/Route 80 in North Branford | 01932-01-011932 | current | |
| Route 139A | — | — | — | — | — | 01964-01-011964 | the last highway log to show this road was the 1948 highway log |
| Route 140 | 22.50 | 36.21 | Route 75 in Windsor Locks | Route 32/Route 190 in Stafford | 01932-01-011932 | current | |
| Route 141 | — | — | — | — | — | 01951-01-011951 | Now Route 22 |
| Route 142 | 4.27 | 6.87 | US 1 in East Haven | US 1/Route 146 in Branford | 01932-01-011932 | current | |
| Route 143 | — | — | — | — | — | 01962-01-011962 | Now Route 146 |
| Route 144 | — | — | — | — | — | 01962-01-011962 | Now Route 80 |
| Route 145 | 9.91 | 15.95 | US 1 in Clinton | Route 148 in Chester | 01932-01-011932 | current | |
| Route 146 | 13.00 | 20.92 | US 1/Route 142 in Branford | US 1 in Guilford | 01932-01-011932 | current | |
| Route 147 | 5.09 | 8.19 | Route 17 in Durham | Route 66 in Middlefield | 01932-01-011932 | current | |
| Route 148 | 16.35 | 26.31 | Route 79 in Killingworth | Route 82 in Lyme | 01932-01-011932 | current | |
| Route 149 | 11.70 | 18.83 | Route 82 in East Haddam | Route 2/Old Hartford Road in Colchester | 01932-01-011932 | current | |
| Route 150 | 9.04 | 14.55 | Route 22 in North Branford | US 5 in Wallingford | 01932-01-011932 | current | Extended in 1962 |
| Route 151 | 10.77 | 17.33 | Route 82 in East Haddam | Route 66 in East Hampton | 01932-01-011932 | current | |
| Route 152 | 3.31 | 5.33 | US 1 in Orange | Route 34 in Orange | 01932-01-011932 | current | |
| Route 153 | 5.27 | 8.48 | US 1 in Westbrook | Route 9/Route 154 in Essex | 01932-01-011932 | current | |
| Route 154 | 28.24 | 45.45 | US 1 in Old Saybrook | Route 9 in Higganum | 01932-01-011932 | current | |
| Route 155 | 2.22 | 3.57 | Route 17 in Middletown | Route 9/Randolph Road in Middletown | 01933-01-011933 | current | |
| Route 156 | 22.76 | 36.63 | Route 82 in East Haddam | US 1 in Waterford | 01932-01-011932 | current | |
| Route 156A | — | — | — | — | — | 01961-01-011961 | |
| Route 157 | 6.86 | 11.04 | Route 68 in Durham | Route 66 in Middletown | 01932-01-011932 | current | |
| Route 158 | — | — | — | — | — | 01950-01-011950 | Now Route 122 |
| Route 159 | 16.82 | 27.07 | Main Street at the Hartford–Windsor town line | Route 159 at the Massachusetts state line | 01968-01-011968 | current | formerly US-5A |
| Route 160 | 7.36 | 11.84 | US 5/Route 15/Berlin Turnpike in Berlin | Route 17 in Glastonbury | 01932-01-011932 | current | |
| Route 161 | 8.03 | 12.92 | Route 156 in East Lyme | Route 85 in Montville | 01932-01-011932 | current | |
| Route 162 | 20.05 | 32.27 | US 1 in Milford | US 1 in Orange | 01932-01-011932 | current | |
| Route 163 | 12.86 | 20.70 | Route 32 in Montville | Route 2 in Bozrah | 01932-01-011932 | current | |
| Route 164 | 7.83 | 12.60 | Route 2 in Preston | Route 138 in Griswold | 01932-01-011932 | current | |
| Route 165 | 16.01 | 25.77 | Route 2 in Norwich | Route 165 at the Rhode Island state line | 01932-01-011932 | current | |
| Route 166 | 1.62 | 2.61 | Route 153 in Westbrook | US 1 in Old Saybrook | 01935-01-011935 | current | |
| Route 167 | 10.41 | 16.75 | Route 4 in Farmington | US 202/Route 10 in Simsbury | 01932-01-011932 | current | |
| Route 168 | 7.93 | 12.76 | Route 168 at the Massachusetts state line | Route 75 in Suffield | 01977-01-011977 | current | Former portion of Route 190 renumbered because of I-190 in Massachusetts |
| Route 169 | 38.25 | 61.56 | Route 2/Route 32 in Norwich | Route 169 at the Massachusetts state line | 01959-01-011959 | current | |
| Route 171 | 20.70 | 33.31 | I-84 in Union | US 44/Route 12 in Putnam | 01959-01-011959 | current | |
| Route 172 | 4.45 | 7.16 | I-84/US 6 in Southbury | Route 67 in Southbury | 01932-01-011932 | current | |
| Route 173 | 6.17 | 9.93 | US 5/Route 15/Berlin Turnpike in Newington | I-84/US 6/South Main Street in West Hartford | 01932-01-011932 | current | |
| Route 174 | 3.18 | 5.12 | Route 9/Route 71/Route 72 in New Britain | Route 176 in Newington | 01932-01-011932 | current | |
| Route 175 | 6.19 | 9.96 | Route 71 in New Britain | Route 99 in Wethersfield | 01932-01-011932 | current | |
| Route 176 | 4.14 | 6.66 | US 5/Route 15/Berlin Turnpike in Newington | Newington Avenue at the Newington–Hartford line | 01932-01-011932 | current | |
| Route 177 | 12.57 | 20.23 | Route 10 in Plainville | US 44/US 202 in Canton | 01932-01-011932 | current | |
| Route 178 | 6.89 | 11.09 | Route 185 in Bloomfield | Route 159 in Windsor | 01932-01-011932 | current | |
| Route 179 | 16.50 | 26.55 | Route 4 in Burlington | Route 20 in Hartland | 01932-01-011932 | current | |
| Route 180 | — | — | — | — | — | 01935-01-011935 | Proposed but never built, Now Route 68 |
| Route 181 | 7.84 | 12.62 | US 44 in Barkhamsted | Route 20 in Hartland | 01932-01-011932 | current | |
| Route 182 | 3.81 | 6.13 | US 44 in Norfolk | Route 182A/Route 183 in Colebrook | 01932-01-011932 | current | |
| Route 182A | 2.09 | 3.36 | Route 182 in Colebrook | Route 182/Route 183 in Colebrook | 01941-01-011941 | current | |
| Route 183 | 19.06 | 30.67 | Route 4 in Torrington | Route 183 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 184 | 15.66 | 25.20 | I-95/US 1/Route 12 in Groton | I-95/Route 216 in North Stonington | 01964-01-011964 | current | |
| Route 185 | 6.36 | 10.24 | US 202/Route 10 in Simsbury | Route 189 in West Hartford | 01932-01-011932 | current | |
| Route 186 | 3.57 | 5.75 | Route 190 in Somers | Route 186 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 187 | 19.74 | 31.77 | US 44 in Hartford | Route 187 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 188 | 15.92 | 25.62 | Route 34 in Seymour | Route 63 in Middlebury | 01935-01-011935 | current | |
| Route 189 | 20.32 | 32.70 | US 44 in Hartford | Route 189 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 190 | 28.27 | 45.50 | Route 75 in Suffield | Route 171 in Union | 01932-01-011932 | current | |
| Route 191 | 9.30 | 14.97 | US 5 in East Windsor | Route 190 in Enfield | 01932-01-011932 | current | |
| Route 192 | 3.49 | 5.62 | Route 190 in Enfield | Route 192 at the Massachusetts state line | 01932-01-011932 | current |
| Route 193 | 6.63 | 10.67 | Route 12 in Thompson | Route 193 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 194 | 3.67 | 5.91 | US 5 in South Windsor | Route 30 in South Windsor | 01932-01-011932 | current | |
| Route 195 | 15.91 | 25.60 | Route 66 in Windham | Route 74 in Tolland | 01932-01-011932 | current | |
| Route 196 | 5.38 | 8.66 | Route 151 in Haddam | Route 66 in East Hampton | 01932-01-011932 | current | |
| Route 197 | 10.97 | 17.65 | Route 171 in Union | Route 197 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 198 | 19.22 | 30.93 | US 6 in Chaplin | Route 198 at the Massachusetts state line | 01932-01-011932 | current | |
| Route 199 | — | — | — | — | — | 01935-01-011935 | Replaced by US 44 |
| Route 199 | 4.62 | 7.44 | Route 67 in Roxbury | Route 47 in Washington | 01935-01-011935 | current | |
| Route 200 | 1.87 | 3.01 | Route 12 in Thompson | Route 193 in Thompson | 01932-01-011932 | current | |
| Route 201 | 20.10 | 32.35 | Route 184 in Stonington | Route 12 in Griswold | 01934-01-011934 | current | |
| Route 202 | — | — | — | — | — | 01935-01-011935 | Renumbered Route 101 because of US 202 |
| Route 203 | 5.32 | 8.56 | Route 32 in Windham | US 6 in Windham | 01932-01-011932 | current | |
| Route 205 | 3.81 | 6.13 | Route 12 in Plainfield | Route 169 in Brooklyn | 01932-01-011932 | current | |
| Route 207 | 16.01 | 25.77 | Route 85 in Hebron | Route 97 in Sprague | 01932-01-011932 | current | |
| Route 209 | 2.93 | 4.72 | Route 109 in Morris | US 202 in Litchfield | 01963-01-011963 | current | |
| Route 211 | — | — | — | — | — | 01950-01-011950 | Now Route 14 |
| Route 213 | 6.66 | 10.72 | Route 156 in Waterford | US 1 in New London | 01932-01-011932 | current | |
| Route 214 | 7.30 | 11.75 | Route 12 in Ledyard | Route 2 in Ledyard | 01963-01-011963 | current | |
| Route 215 | 4.65 | 7.48 | US 1 in Groton | US 1 in Groton | 01932-01-011932 | current | |
| Route 216 | 2.78 | 4.47 | Route 49 in North Stonington | Route 216 at the Rhode Island state line | 01934-01-011934 | current | |
| Route 217 | 3.84 | 6.18 | Route 66 in Middlefield | Route 372 in Cromwell | 01963-01-011963 | current | |
| Route 218 | 7.00 | 11.27 | US 44 in West Hartford | I-291/Route 159 in Windsor | 01935-01-011935 | current | |
| Route 219 | 14.98 | 24.11 | US 202 in New Hartford | Route 20 in Granby | 01935-01-011935 | current | |
| Route 220 | 5.80 | 9.33 | US 5 in Enfield | Route 220 at the Massachusetts state line | 01936-01-011936 | current | |
| Route 222 | 8.08 | 13.00 | US 6/Route 8 in Thomaston | Route 118 in Harwinton | 01963-01-011963 | current | |
| Route 229 | 5.94 | 9.56 | I-84 in Southington | US 6 in Bristol | 01963-01-011963 | current | |
| Route 234 | 6.95 | 11.18 | Route 27 in Stonington | US 1 in Stonington | 01987-01-011987 | current | |
| Route 243 | 6.70 | 10.78 | Route 115 in Ansonia | Route 63 in New Haven | 01963-01-011963 | current | |
| Route 244 | 5.72 | 9.21 | Route 198 in Eastford | Route 97 in Pomfret | 01988-01-011988 | current | |
| Route 254 | 8.41 | 13.53 | US 6/Route 8 in Thomaston | Route 118 in Litchfield | 01963-01-011963 | current | |
| Route 262 | 9.37 | 15.08 | US 6 in Watertown | US 6 in Plymouth | 01963-01-011963 | current | |
| Route 263 | 6.23 | 10.03 | Route 272 in Goshen | US 44/Route 183 in Winchester | 01963-01-011963 | current | |
| Route 272 | 17.97 | 28.92 | Route 4 in Torrington | Norfolk Road at the Massachusetts state line | 01963-01-011963 | current | |
| Route 275 | 4.15 | 6.68 | Route 31 in Coventry | Route 195 in Mansfield | 01963-01-011963 | current | |
| Route 286 | 3.60 | 5.79 | Route 74 in Ellington | Route 83 in Ellington | 01963-01-011963 | current | |
| Route 287 | 3.36 | 5.41 | Route 176 in Newington | Route 3 in Wethersfield | 01970-01-011970 | current | |
| Route 289 | 5.13 | 8.26 | Route 87 in Lebanon | Route 32 in Windham | 01964-01-011964 | current | |
| Route 291 | — | — | — | — | 01958-01-011958 | 01994-01-011994 | Now I-291 |
| Route 302 | 7.96 | 12.81 | Route 53 in Bethel | Route 25 in Newtown | 01974-01-011974 | current | |
| Route 305 | 3.42 | 5.50 | Route 187 in Bloomfield | Route 75 in Windsor | 01963-01-011963 | current | |
| Route 309 | 4.74 | 7.63 | Route 179 in Canton | Route 167 in Simsbury | 01963-01-011963 | current | |
| Route 313 | 6.85 | 11.02 | Route 8/Route 67 in Seymour | Route 243 in Woodbridge | 01963-01-011963 | current | |
| Route 314 | 2.07 | 3.33 | US 5/Route 15/Berlin Turnpike in Wethersfield | Route 99 in Wethersfield | 01963-01-011963 | current | |
| Route 315 | 1.95 | 3.14 | US 202/Route 10 in Simsbury | Route 189 in Simsbury | 01963-01-011963 | current | |
| Route 316 | 6.04 | 9.72 | Route 66 in Hebron | US 6 in Andover | 01963-01-011963 | current | |
| Route 317 | 6.10 | 9.82 | Route 67 in Roxbury | US 6 in Woodbury | 01964-01-011964 | current | |
| Route 318 | 3.14 | 5.05 | US 44 in Barkhamsted | Route 219 in Barkhamsted | 01963-01-011963 | current | |
| Route 319 | 2.83 | 4.55 | Route 190 in Stafford | Route 19 in Stafford | 01988-01-011988 | current | |
| Route 320 | 7.05 | 11.35 | Route 195 in Mansfield | I-84 in Willington | 01963-01-011963 | current | |
| Route 322 | 9.80 | 15.77 | Route 69 in Wolcott | I-691 in Southington | 01963-01-011963 | current | |
| Route 334 | 4.40 | 7.08 | Route 188 in Seymour | Route 115 in Ansonia | 01963-01-011963 | current | |
| Route 337 | 4.91 | 7.90 | I-95/US 1 in New Haven | Route 142 in East Haven | 01987-01-011987 | current | |
| Route 341 | 15.97 | 25.70 | CR 3 at the New York state line | US 202 in Washington | 01932-01-011932 | current | |
| Route 343 | 1.50 | 2.41 | NY 343 at the New York state line | Route 4/Route 41 in Sharon | 01932-01-011932 | current | |
| Route 349 | 4.17 | 6.71 | Shennecossett Road in Groton | I-95/US 1 in Groton | 01985-01-011985 | current | |
| Route 354 | 7.37 | 11.86 | Route 85 in Colchester | Route 82 in Salem | 01963-01-011963 | current | |
| Route 361 | 3.54 | 5.70 | Route 41 in Sharon | CR 62 at the New York state line | 01966-01-011966 | current | |
| Route 364 | 4.56 | 7.34 | Route 120 in Southington | Route 71 in Berlin | 01964-01-011964 | current | |
| Route 372 | 15.12 | 24.33 | Route 72/East Main Street in Plainville | Route 99 in Cromwell | 01978-01-011978 | current | |

## Special Service Roads

Roads classified by the Department of Transportation as special service roads are given an unsigned number designation between 400 and 499. Special service roads are roads that connect a federal or state facility (including state parks and some Interstate Highway interchanges) to a signed state route. These numbers only appear in internal documentation, none of them are signed.

## State Roads

State Roads are state-maintained roads that are usually long entrance/exit ramps to/from an expressway, or short interconnecting roads between signed routes. Roads classified by the Department of Transportation as state roads are given an unsigned number designation between 500 and 999. The first digit denotes which Maintenance District the road is mainly located in:
* 500–599: District 1: Greater Hartford
* 600–699: District 2: Quiet Corner, Lower Connecticut River Valley, Southeastern Connecticut
* 700–799: District 3: Southwestern Connecticut, Greater New Haven
* 800–899: District 4: Naugatuck River Valley, Greater Danbury, Northwestern Connecticut
* 900–999: Statewide; very short routes
State road numbers are only for internal record-keeping and documentation, all of these roads are unsigned.

## History
### 1913 trunk line system

In 1900, the State Highway Department proposed a statewide system of trunk line routes. By 1913, the system consisted of 10 north-south highways and 4 east-west highways, including the lower Boston Post Road. The system covered roughly 1,400 miles (2,300 km). The 14 trunk lines were numbered on paper but were never actually signposted. The 14 trunk line routes were:
* Route 1: east-west from Greenwich to Stonington, roughly modern U.S. Route 1
* Route 2: north-south from Stamford to Salisbury, roughly modern Route 106, Route 33, Route 35, U.S. Route 7, Route 341, Route 41
* Route 3: north-south from Norwalk to North Canaan, roughly modern U.S. Route 7, Route 107, Route 53, Route 37, U.S. Route 202, Route 45, U.S. Route 7
* Route 4: north-south from Bridgeport to Colebrook, roughly modern Route 8
* Route 5: north-south from New Haven to Suffield via Cheshire (concurrent with Route 6 north of Hartford), roughly modern Route 10, Route 4, Route 159
* Route 6: north-south from New Haven to Suffield via Meriden (concurrent with Route 5 north of Hartford), roughly modern U.S. Route 5, Route 71, Route 159
* Route 7: north-south from New Haven to Enfield via Middletown, roughly modern Route 17, Route 99, U.S. Route 5
* Route 8: north-south from Old Saybrook to Hartford, roughly modern Route 9, Route 99
* Route 9: north-south from New London to Colebrook, roughly modern Route 85, Route 2, Route 189, Route 20
* Route 10: north-south from New London to Thompson, roughly modern Route 32, Route 169, Route 12, Route 193
* Route 11: north-south from Stonington to Woodstock, roughly modern Route 2, Route 32, U.S. Route 6, Route 198
* Route 12: east-west from Salisbury to Putnam, roughly Twin Lakes Road, modern U.S. Route 44
* Route 13: east-west from Kent to Sterling, roughly modern Route 341, U.S. Route 202, Route 118, Route 4, U.S. Route 6, Route 14
* Route 14: east-west from Sherman to Killingly, roughly Route 37, Route 67, Route 317, Route 64, Route 322, Route 66, U.S. Route 6

### New England road marking system

The first public route numbering came with the advent of the New England road marking system of 1922. This highway numbering system was used throughout New England and consisted of 25 routes (with route numbers from 1 to 32). A total of 9 of the routes passed through Connecticut (Routes 1, 2, 3, 4, 8, 10, 12, 17, and 32). In this system, inter-state routes would be numbered 1–99 and state routes numbered 100 and up. The New England route system was soon eclipsed by the national U.S. highway system.

### 1922–1931

The State Highway Department classified state roads as either State Highways (SH) or State Aid Roads (SA). These roads were given number designations – 100–299 for primary routes and 300+ for secondary routes. Some state roads were signposted and some were not.

### 1932 renumbering

The state abandoned its old numbering system and renumbered almost all of their state highways in 1932. Most of the present route numbers were formed during this renumbering. The only route numbers that survived were U.S. Routes and a few state highway routes. For route numbers established in 1932, the new numbering system used odd numbers for north-south routes and even numbers for east-west routes, matching the U.S. Highway numbering system. The New England routes that were grandfathered into the highway system (Routes 8, 10, 12, 32) did not follow the new system. The state also assigned new route numbers in clusters, with routes in the same general location having numbers close to each other as well. Shortly after the renumbering, in 1935, two new U.S. Routes were commissioned: US 44 (taking over part of old New England Route 17) and US 202.

### 1963 renumbering

In 1963, the state passed the Road Reclassification Act to fix the by now fragmented state highway system. Many state highways had state maintenance gaps and several highway segments were even isolated from the rest of the system. State highways were classified into primary, secondary, and service roads. Primary routes were essentially left unchanged, while minor realignments, additions/deletions, and extensions occurred in many secondary routes. About 1/3 of all routes were changed to some degree by this renumbering. The current system of unsigned ("secret") routes, including the special service roads, was also created during this renumbering. The state highway system has not had any major changes since then. The state completely abandoned the odd/even numbering scheme established in 1932 with new numbers in 1963 assigned without regard to their direction or general location.