# List of U.S. Highways in Maine
## Primary routes

Note about termini: In several cases there is disagreement between the administrative termini of a route (which is defined by MaineDOT) and the termini signed in the field. All termini listed on this page are administrative termini; discrepancies are listed on the respective pages.
| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| US 1 | 527.19 | 848.43 | US 1 in Portsmouth, NH | Route 161 in Clair, NB | 01926-01-011926 | current | Mostly follows the old New England Route 1 and New England Route 24 |
| US 2 | 273.64 | 440.38 | US 2 in Shelburne, NH | I-95 in Houlton | 01926-01-011926 | current | Mostly follows the old New England Route 15 |
| US 201 | 157.46 | 253.41 | US 1 / SR 24 in Brunswick | SR 6 / Route 173 near Saint-Theophile, QC | 01926-01-011926 | current | Mostly follows the old New England Route 20 |
| US 202 | 168.52 | 271.21 | US 202 / NH 11 in Rochester, NH | I-395 / US 1A / SR 15 in Bangor | 01936-01-011936 | current | Currently signed with US 1A into downtown Bangor at US 2, but was truncated to I-395 in 1989. Does not officially intersect with US 2. |
| US 302 | 54.15 | 87.15 | US 302 in Conway, NH | I-295 / US 1 / SR 100 in Portland | 01935-01-011935 | current | Mostly follows the old New England Route 18 Currently signed with SR 100 to end at Park Ave (formerly US 1), but was truncated in 2007 when US 1 was shifted onto I-295. |

## Alternate and auxiliary routes

| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| US 1 Byp. | 1.5 | 2.4 | US 1 Byp. in Portsmouth | US 1 in Kittery | 01960-01-01c. 1960 | current | Originally designated US 1A, also designated I-95 until 1972 |
| US 1 Bus. | 3.4 | 5.5 | US 1 in Newcastle | US 1 in Damariscotta | 01963-01-011963 | current | Formerly US 1 |
| US 1 Bus. | 3.6 | 5.8 | — | — | 01951-01-011951 | 01960-01-011960 | Former alignment of US 1, redesignated US 1 in 1960 |
| US 1 Bus. | 2.6 | 4.2 | — | — | 01955-01-011955 | 01956-01-011956 | Redesignated US 1A Business, which was later decommissioned |
| US 1A | 7.0 | 11.3 | US 1 in York | US 1 in York | 01936-01-011936 | current | York segment |
| US 1A | 3.5 | 5.6 | I-295 / US 1 in Portland | I-295 / US 1 in Portland | 01951-01-011951 | current | Portland segment |
| US 1A | 1.6 | 2.6 | US 1 in Rockland | US 1 in Rockland | 01941-01-011941 | current | Rockland segment; redesignated US 1 Bypass in 1963 but reverted to US 1A in 1987 |
| US 1A | 54.0 | 86.9 | US 1 / SR 3 in Stockton Springs | US 1 / SR 3 in Ellsworth | 01966-01-011966 | current | Stockton Springs-Ellsworth segment; formerly US 1 |
| US 1A | 7.8 | 12.6 | US 1 in Milbridge | US 1 in Harrington | 01936-01-011936 | current | Milbridge-Harrington segment |
| US 1A | 8.1 | 13.0 | US 1 in Jonesboro | US 1 in Machias | 01936-01-011936 | current | Jonesboro-Machias segment |
| US 1A | 49.8 | 80.1 | US 1 in Mars Hill | US 1 in Van Buren | 01940-01-011940 | current | Mars Hill-Van Buren segment, formerly US 1. |
| US 1A Bus. | — | — | — | — | 01955-01-011955 | — | Unsigned designation for a former alignment of US 1 in Bangor, now unnumbered. |
| US 2A | 4.6 | 7.4 | US 2 in Orono | US 2 / SR 43 in Old Town | 01954-01-011954 | current | Southern segment, formerly US 2 |
| US 2A | 43.5 | 70.0 | US 2 in Macwahoc Plantation | US 1 / US 2 in Houlton | 01936-01-011936 | current | Northern segment, formerly SR 166 |
| US 201A | 26.18 | 42.13 | US 2 / US 201 / SR 104 in Skowhegan | US 201 / SR 8 in Solon | 01954-01-011954 | current | Formerly US 201; now completely overlaid with other routes |
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