# Rhestr o Siroedd Ohio

Siroedd Ohio
Dyma **restr o'r 88 rhanbarth gweinyddol sy'n cael eu hadnabod wrth yr enw *County* yn Nhalaith Ohio yn yr Unol Daleithiau, yn nhrefn yr wyddor:**

## Rhestr

### FIPS

Mae'r cod Safon Prosesu Gwybodaeth Ffederal (FIPS), a ddefnyddir gan lywodraeth yr Unol Daleithiau i roi cod hunaniaeth unigryw i daleithiau a siroedd y wlad, yn cael ei ddarparu gyda phob cofnod yn y tabl. Cod Ohio yw 39, a fyddai, o'i gyfuno ag unrhyw god sirol, yn cael ei ysgrifennu fel 39XXX. Mae Adams County yn rhannu'r cod 001 gyda nifer o siroedd eraill yn yr Unol Daleithiau megis Allegany County, Maryland ond o ragddodi cod talaith Ohio, 39, i cod Adams County ceir 39001, cod unigryw i'r sir honno.

| Sir
 | Cod FIPS
 | Sedd sirol
 | Sefydlu
 | Tarddiad
 | Etymoleg
 | Poblogaeth
 | Maint
 | Map
 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Adams County
 | 001
 | West Union | 10 Gorffennaf, 1797 | Hamilton County | John Adams (1735-1826), Arlywydd yr Unol Daleithiau pan drefnwyd y sir
 | 700428550000000000028,550
 | 7002583910000000000583.91 sq mi (70031512000000000001,512 km2) |  |
| Allen County
 | 003
 | Lima | 1 Mawrth, 1820 | Shelby County | John Allen (1771 / 2-1813), cyrnol yn Rhyfel 1812
 | 7005106331000000000106,331
 | 7002404430000000000404.43 sq mi (70031047000000000001,047 km2) |  |
| Ashland County
 | 005
 | Ashland | 24 Chwefror, 1846 | Wayne County, Richland County, Huron County, a Lorain County | Ashland, cartref Seneddwr yr Unol Daleithiau o Kentucky Henry Clay.
 | 700453139000000000053,139
 | 7002424370000000000424.37 sq mi (70031099000000000001,099 km2) |  |
| Ashtabula County
 | 007
 | Jefferson | 7 Mehefin, 1807 | Trumbull County a Geauga County | Afon Ashtabula , sy'n golygu "afon bysgod" mewn iaith frodorol yr Algonquin
 | 7005101497000000000101,497
 | 7002702440000000000702.44 sq mi (70031819000000000001,819 km2) |  |
| Athens County
 | 009
 | Athens | 1 Mawrth, 1805 | Washington County | Athen yng Ngwlad Groeg
 | 700464757000000000064,757
 | 7002506760000000000506.76 sq mi (70031313000000000001,313 km2) |  |
| Auglaize County
 | 011
 | Wapakoneta | 14 Chwefror, 1848 | Allen County, Mercer County, Darke County, Hardin County, Logan County, Shelby County, a Van Wert County | Afon Auglaize, sy'n golygu "afon goed wedi cwympo" yn iaith frodorol y Shawnee
 | 700445949000000000045,949
 | 7002401250000000000401.25 sq mi (70031039000000000001,039 km2) |  |
| Belmont County
 | 013
 | St. Clairsville | 7 Medi, 1801 | Jefferson County a Washington County | Belle monte, sy'n golygu "mynydd hardd" yn y Ffrangeg
 | 700470400000000000070,400
 | 7002537350000000000537.35 sq mi (70031392000000000001,392 km2) |  |
| Brown County
 | 015
 | Georgetown | 1 Mawrth, 1818 | Adams County a Clermont County | Y Cadfridog Jacob Brown (1775-1828), swyddog yn Rhyfel 1812
 | 700444846000000000044,846
 | 7002491760000000000491.76 sq mi (70031274000000000001,274 km2) |  |
| Butler County
 | 017
 | Hamilton | 1 Mai, 1803 | Hamilton County | Y Cadfridog Richard Butler (1743–1791), a laddwyd ym Mrwydr y Wabash
 | 7005368130000000000368,130
 | 7002467270000000000467.27 sq mi (70031210000000000001,210 km2) |  |
| Carroll County
 | 019
 | Carrollton | 1 Ionawr, 1833 | Columbiana County, Stark County, Harrison County, Jefferson County, a Tuscarawas County | Charles Carroll (1737-1832), arwyddwr olaf Datganiad Annibyniaeth yr Unol Daleithiau
 | 700428836000000000028,836
 | 7002394670000000000394.67 sq mi (70031022000000000001,022 km2) |  |
| Champaign County
 | 021
 | Urbana | 1 Mawrth, 1805 | Greene County a Franklin County | Ffrangeg am "wastadedd", yn disgrifio'r tir yn yr ardal
 | 700440097000000000040,097
 | 7002428560000000000428.56 sq mi (70031110000000000001,110 km2) |  |
| Clark County
 | 023
 | Springfield | 1 Mawrth, 1818 | Champaign County, Madison County, a Greene County | Y Cadfridog George Rogers Clark (1752-1818) a orchfygodd llwyth brodorol y Shawnee mewn brwydr ger ardal Springfield
 | 7005138333000000000138,333
 | 7002399860000000000399.86 sq mi (70031036000000000001,036 km2) |  |
| Clermont County
 | 025
 | Batavia | 6 Rhagfyr, 1800 | Hamilton County | Ffrangeg am "mynydd clir"
 | 7005197363000000000197,363
 | 7002451990000000000451.99 sq mi (70031171000000000001,171 km2) |  |
| Clinton County
 | 027
 | Wilmington | 1 Mawrth, 1810 | Highland County a Warren County | George Clinton (1739-1812), is-lywydd yr UD pan drefnwyd y sir
 | 700442040000000000042,040
 | 7002410880000000000410.88 sq mi (70031064000000000001,064 km2) |  |
| Columbiana County
 | 029
 | Lisbon | 1 Mai, 1803 | Jefferson County a Washington County | Christopher Columbus
 | 7005107841000000000107,841
 | 7002532460000000000532.46 sq mi (70031379000000000001,379 km2) |  |
| Coshocton County
 | 031
 | Coshocton | 31 Ionawr, 1810 | Muskingum County a Tuscarawas County | Gair llwyth y Delaware sy'n golygu "cymer dyfroedd"
 | 700436901000000000036,901
 | 7002564070000000000564.07 sq mi (70031461000000000001,461 km2) |  |
| Crawford County
 | 033
 | Bucyrus | 1 Ebrill, 1820 | Delaware County | Cyrnol William Crawford (1732–1782), swyddog yn Rhyfel Annibyniaeth America
 | 700443784000000000043,784
 | 7002402110000000000402.11 sq mi (70031041000000000001,041 km2) |  |
| Cuyahoga County
 | 035
 | Cleveland | 7 Mehefin, 1807 | Geauga County | Afon Cuyahoga , sy'n golygu "afon gam" yn yr iaith Iroquoaidd
 | 70061249352000000001,249,352
 | 7002458490000000000458.49 sq mi (70031187000000000001,187 km2) |  |
| Darke County
 | 037
 | Greenville | 3 Ionawr, 1809 | Miami County | Cadfridog William Darke (1736–1801), swyddog yn Rhyfel Annibyniaeth America
 | 700452959000000000052,959
 | 7002599790000000000599.80 sq mi (70031553000000000001,553 km2) |  |
| Defiance County
 | 039
 | Defiance | 7 Ebrill, 1845 | Williams County, Henry County a Paulding County | Fort Defiance, a adeiladwyd ym 1794 gan y Cadfridog Anthony Wayne
 | 700439037000000000039,037
 | 7002411160000000000411.16 sq mi (70031065000000000001,065 km2) |  |
| Delaware County
 | 041
 | Delaware | 1 Ebrill, 1808 | Franklin County | Llwyth brodorol y Delaware
 | 7005174214000000000174,214
 | 7002442410000000000442.41 sq mi (70031146000000000001,146 km2) |  |
| Erie County
 | 043
 | Sandusky | 15 Mawrth, 1838 | Huron County a Sandusky County | Llwyth brodorol yr Erie
 | 700477079000000000077,079
 | 7002254880000000000254.88 sq mi (7002660000000000000660 km2) |  |
| Fairfield County
 | 045
 | Lancaster | 9 Rhagfyr, 1800 | Ross County a Washington County | Y Saesneg am "gaeau teg"
 | 7005146156000000000146,156
 | 7002505110000000000505.11 sq mi (70031308000000000001,308 km2) |  |
| Fayette County
 | 047
 | Washington Court House | 1 Mawrth, 1810 | Ross County | Gilbert du Motier, marquis de La Fayette , swyddog milwrol Ffrengig ac aristocrat a gymerodd ran yn y chwyldroadau Americanaidd a Ffrengig.
 | 700429030000000000029,030
 | 7002406580000000000406.58 sq mi (70031053000000000001,053 km2) |  |
| Franklin County
 | 049
 | Columbus | 30 Ebrill, 1803 | Ross County a Wayne County | Benjamin Franklin (1706–1791), Tad Sylfaenol, awdur, argraffydd, damcaniaethwr gwleidyddol, gwyddonydd, dyfeisiwr, a gwladweinydd
 | 70061264518000000001,264,518
 | 7002539870000000000539.87 sq mi (70031398000000000001,398 km2) |  |
| Fulton County
 | 051
 | Wauseon | 1 Ebrill, 1850 | Lucas County, Henry County, a Williams County | Robert Fulton (1765-1815), dyfeisiwr yr agerlong
 | 700442698000000000042,698
 | 7002406789999900000406.78 sq mi (70031054000000000001,054 km2) |  |
| Gallia County
 | 053
 | Gallipolis | 30 Ebrill, 1803 | Washington County ac Adams County | Gâl, enw hynafol Ffrainc
 | 700430934000000000030,934
 | 7002468780000000000468.78 sq mi (70031214000000000001,214 km2) |  |
| Geauga County
 | 055
 | Chardon | 1 Mawrth, 1806 | Trumbull County | Enw brodorol am yr anifail "raccoon" (*Procyon lotor*)
 | 700493389000000000093,389
 | 7002403660000000000403.66 sq mi (70031045000000000001,045 km2) |  |
| Greene County
 | 057
 | Xenia | 1 Mai, 1803 | Hamilton County a Ross County | Y Cadfridog Nathanael Greene (1742–1786), swyddog yn Rhyfel Annibyniaeth America
 | 7005161573000000000161,573
 | 7002414880000000000414.88 sq mi (70031075000000000001,075 km2) |  |
| Guernsey County
 | 059
 | Cambridge | 1 Mawrth, 1810 | Belmont County a Muskingum County | Ynys Guernsey, o ble y tarddodd y mwyafrif o'r ymsefydlwyr
 | 700440087000000000040,087
 | 7002521900000000000521.90 sq mi (70031352000000000001,352 km2) |  |
| Hamilton County
 | 061
 | Cincinnati | 2 Ionawr, 1790 | Un o'r siroedd gwreiddiol | Alexander Hamilton (1755 / 7-1804), Ysgrifennydd y Trysorlys pan drefnwyd y sir
 | 7005802374000000000802,374
 | 7002407360000000000407.36 sq mi (70031055000000000001,055 km2) |  |
| Hancock County
 | 063
 | Findlay | 1 Ebrill, 1820 | Logan County | John Hancock (1737–1793), llywydd y Gyngres Gyfandirol
 | 700474782000000000074,782
 | 7002531350000000000531.35 sq mi (70031376000000000001,376 km2) |  |
| Hardin County
 | 065
 | Kenton | 1 Ebrill, 1820 | Logan County | Y Cadfridog John Hardin (1753–1792), swyddog yn Rhyfel Annibyniaeth America
 | 700432058000000000032,058
 | 7002470290000000000470.29 sq mi (70031218000000000001,218 km2) |  |
| Harrison County
 | 067
 | Cadiz | 1 Chwefror, 1813 | Jefferson County a Tuscarawas County | Y Cadfridog William Henry Harrison (1773–1841), swyddog yn Rhyfel 1812 ac wedyn yn Arlywydd yr Unol Daleithiau
 | 700415864000000000015,864
 | 7002403539999900000403.53 sq mi (70031045000000000001,045 km2) |  |
| Henry County
 | 069
 | Napoleon | 1 Ebrill, 1820 | Shelby County | Patrick Henry (1736–1799), Deddfwr yng nghyfnod Rhyfel Annibyniaeth America, areithiwr, ac ysgolhaig
 | 700428215000000000028,215
 | 7002416500000000000416.50 sq mi (70031079000000000001,079 km2) |  |
| Highland County
 | 071
 | Hillsboro | 1 Mai, 1805 | Ross County, Adams County, a Clermont County | Y Saesneg am "ucheldir", disgrifiadol o dir y sir
 | 700443589000000000043,589
 | 7002553280000000000553.28 sq mi (70031433000000000001,433 km2) |  |
| Hocking County
 | 073
 | Logan | 1 Mawrth, 1818 | Athens County, Ross County a Fairfield County | Yn deillio o bosib o air yn iaith llwyth y Delaware "Hoch-Hoch-ing", sy'n golygu "potel"
 | 700429380000000000029,380
 | 7002422750000000000422.75 sq mi (70031095000000000001,095 km2) |  |
| Holmes County
 | 075
 | Millersburg | 20 Ionawr, 1824 | Coshocton County, Wayne County a Tuscarawas County | Yr Uwchgapten Andrew Holmes (bu farw 1814), swyddog yn Rhyfel 1812
 | 700442366000000000042,366
 | 7002422990000000000422.99 sq mi (70031096000000000001,096 km2) |  |
| Huron County
 | 077
 | Norwalk | 7 Mawrth, 1809 | Portage County a Cuyahoga County | Llwyth brodorol y Huron
 | 700459626000000000059,626
 | 7002492690000000000492.69 sq mi (70031276000000000001,276 km2) |  |
| Jackson County
 | 079
 | Jackson | 1 Mawrth, 1816 | Scioto County, Gallia County, Athens County a Ross County | Andrew Jackson (1767–1845), Arlywydd yr Unol Daleithiau
 | 700433225000000000033,225
 | 7002420289999900000420.28 sq mi (70031089000000000001,089 km2) |  |
| Jefferson County
 | 081
 | Steubenville | 29 Gorffennaf, 1797 | Washington County | Thomas Jefferson (1743–1826)
 | 700469709000000000069,709
 | 7002409610000000000409.61 sq mi (70031061000000000001,061 km2) |  |
| Knox County
 | 083
 | Mount Vernon | 1 Mawrth, 1808 | Fairfield County | Y Cadfridog Henry Knox, yr Ysgrifennydd Rhyfel cyntaf
 | 700460921000000000060,921
 | 7002527120000000000527.12 sq mi (70031365000000000001,365 km2) |  |
| Lake County
 | 085
 | Painesville | 6 Mawrth, 1840 | Geauga County a Cuyahoga County | Ei leoliad ar Lyn Erie
 | 7005230041000000000230,041
 | 7002228210000000000228.21 sq mi (7002591000000000000591 km2) |  |
| Lawrence County
 | 087
 | Ironton | 21 Rhagfyr, 1815 | Gallia County a Scioto County | Y Capten James Lawrence (1781–1813), arwr llyngesol yn Rhyfel 1812
 | 700462450000000000062,450
 | 7002454960000000000454.96 sq mi (70031178000000000001,178 km2) |  |
| Licking County
 | 089
 | Newark | 1 Mawrth, 1808 | Fairfield County | Wedi'i enwi ar gyfer y "llyfiadau" halen yn yr ardal
 | 7005166492000000000166,492
 | 7002686500000000000686.50 sq mi (70031778000000000001,778 km2) |  |
| Logan County
 | 091
 | Bellefontaine | 1 Mawrth, 1818 | Champaign County | Cadfridog Benjamin Logan (tua 1742 - 1802), a ddinistriodd drefi llwyth y Shawnee yn y sir
 | 700445858000000000045,858
 | 7002458440000000000458.44 sq mi (70031187000000000001,187 km2) |  |
| Lorain County
 | 093
 | Elyria | 26 Rhagfyr, 1822 | Huron County, Cuyahoga County a Medina County | Talaith Lorraine, Ffrainc
 | 7005301356000000000301,356
 | 7002492500000000000492.50 sq mi (70031276000000000001,276 km2) |  |
| Lucas County
 | 095
 | Toledo | 20 Mehefin, 1835 | Wood County, Sandusky County a Huron County | Robert Lucas (1781-1853), Llywodraethwr Ohio pan gafodd y sir ei chreu
 | 7005441815000000000441,815
 | 7002340460000000000340.46 sq mi (7002882000000000000882 km2) |  |
| Madison County
 | 097
 | London | 1 Mawrth, 1810 | Franklin County | James Madison (1751–1836), Arlywydd yr Unol Daleithiau
 | 700443435000000000043,435
 | 7002465440000000000465.44 sq mi (70031205000000000001,205 km2) |  |
| Mahoning County
 | 099
 | Youngstown | 1 Mawrth, 1846 | Columbiana County a Trumbull County | Afon Mahoning , o air Lenape sy'n golygu *ger y lle hallt* | 7005238823000000000238,823
 | 7002415250000000000415.25 sq mi (70031075000000000001,075 km2) |  |
| Marion County
 | 101
 | Marion | 1 Ebrill, 1820 | Delaware County | Cadfridog Francis Marion (1732–1795), is-gyrnol yn y Fyddin Gyfandirol ac yn ddiweddarach Brigadydd Cyffredinol yn Rhyfel Annibyniaeth America.
 | 700466501000000000066,501
 | 7002403849999900000403.84 sq mi (70031046000000000001,046 km2) |  |
| Medina County
 | 103
 | Medina | 18 Chwefror, 1812 | Portage County | Medina, Saudi Arabia
 | 7005176395000000000176,395
 | 7002423000000000000423 sq mi (70031096000000000001,096 km2) |  |
| Meigs County
 | 105
 | Pomeroy | 1 Ebrill, 1819 | Gallia County a Athens County | Return Jonathan Meigs, Jr (1764-1825), Llywodraethwr Ohio a Phostfeistr Cyffredinol ar yr adeg y trefnwyd y sir
 | 700423770000000000023,770
 | 7002429420000000000429.42 sq mi (70031112000000000001,112 km2) |  |
| Mercer County
 | 107
 | Celina | 1 Ebrill, 1820 | Darke County | Y Cadfridog Hugh Mercer (1726–1777), swyddog yn Rhyfel Annibyniaeth America
 | 700440814000000000040,814
 | 7002463270000000000463.27 sq mi (70031200000000000001,200 km2) |  |
| Miami County
 | 109
 | Troy | 1 Mawrth, 1807 | Montgomery County | Llwyth brodorol y Miami
 | 7005102506000000000102,506
 | 7002407040000000000407.04 sq mi (70031054000000000001,054 km2) |  |
| Monroe County
 | 111
 | Woodsfield | 29 Ionawr, 1813 | Belmont County, Washington County a Guernsey County | James Monroe (1758–1831)
 | 700414642000000000014,642
 | 7002455540000000000455.54 sq mi (70031180000000000001,180 km2) |  |
| Montgomery County
 | 113
 | Dayton | 1 Mai, 1803 | Hamilton County a Wayne County | Y Cadfridog Richard Montgomery (1738–1775), swyddog yn Rhyfel Annibyniaeth America
 | 7005535153000000000535,153
 | 7002461680000000000461.68 sq mi (70031196000000000001,196 km2) |  |
| Morgan County
 | 115
 | McConnelsville | 29 Rhagfyr, 1817 | Washington County, Guernsey County a Muskingum County | Y Cadfridog Daniel Morgan (c. 1735 – 1802), swyddog yn Rhyfel Annibyniaeth America
 | 700415054000000000015,054
 | 7002417660000000000417.66 sq mi (70031082000000000001,082 km2) |  |
| Morrow County
 | 117
 | Mount Gilead | 1 Mawrth, 1848 | Knox County, Marion County, Delaware County a Richland County | Jeremiah Morrow (1771–1852), Llywodraethwr Ohio
 | 700434827000000000034,827
 | 7002406220000000000406.22 sq mi (70031052000000000001,052 km2) |  |
| Muskingum County
 | 119
 | Zanesville | 1 Mawrth, 1804 | Washington County a Fairfield County | Gair Indiaid sy'n golygu "Tref ger yr afon"
 | 700486074000000000086,074
 | 7002664630000000000664.63 sq mi (70031721000000000001,721 km2) |  |
| Noble County
 | 121
 | Caldwell | 1 Ebrill, 1851 | Monroe County, Washington County, Morgan County a Guernsey County | James Noble (1785-1831), gwladychwr cynnar a Seneddwr yr Unol Daleithiau yn y dyfodol o Indiana
 | 700414645000000000014,645
 | 7002399000000000000399.00 sq mi (70031033000000000001,033 km2) |  |
| Ottawa County
 | 123
 | Port Clinton | 6 Mawrth, 1840 | Erie County, Sandusky County a Lucas County | Enwyd ar gyfer llwyth yr Ottawa ; Ystyr Ottawa yw "masnachwr" yn eu hiaith
 | 700441428000000000041,428
 | 7002254950000000000254.95 sq mi (7002660000000000000660 km2) |  |
| Paulding County
 | 125
 | Paulding | 1 Ebrill, 1820 | Darke County | John Paulding (1758-1818), cipiwr yr ysbïwr John André yn ystod Rhyfel Annibyniaeth America
 | 700419614000000000019,614
 | 7002416260000000000416.26 sq mi (70031078000000000001,078 km2) |  |
| Perry County
 | 127
 | New Lexington | 1 Mawrth, 1818 | Washington County, Fairfield County a Muskingum County | Comodor Oliver Hazard Perry (1785–1819), swyddog llyngesol yn ystod Rhyfel 1812
 | 700436058000000000036,058
 | 7002409789999900000409.78 sq mi (70031061000000000001,061 km2) |  |
| Pickaway County
 | 129
 | Circleville | 1 Mawrth, 1810 | Ross County, Fairfield County a Franklin County | Camsillafiad o enw llwyth y Piqua, cangen o'r Shawnee
 | 700455698000000000055,698
 | 7002501910000000000501.91 sq mi (70031300000000000001,300 km2) |  |
| Pike County
 | 131
 | Waverly | 1 Chwefror, 1815 | Ross County, Scioto County a Adams County | General Zebulon M. Pike (1779–1813), swyddog Rhyfel 1812 a darganfyddwr Pikes Peak yn Colorado ym 1806
 | 700428709000000000028,709
 | 7002441490000000000441.49 sq mi (70031143000000000001,143 km2) |  |
| Portage County
 | 133
 | Ravenna | 7 Gorffennaf, 1807 | Trumbull County | O'r gair Saesneg *portage*, i gario cwch dros ddarn o dir
 | 7005161419000000000161,419
 | 7002492390000000000492.39 sq mi (70031275000000000001,275 km2) |  |
| Preble County
 | 135
 | Eaton | 1 Mawrth, 1808 | Montgomery County a Butler County | Y Captain Edward Preble (1761–1807), swyddog llyngesol yn Rhyfel Annibyniaeth America
 | 700442270000000000042,270
 | 7002424800000000000424.80 sq mi (70031100000000000001,100 km2) |  |
| Putnam County
 | 137
 | Ottawa | 1 Ebrill, 1820 | Shelby County | Y Cadfridog Israel Putnam (1718–1790), swyddog yn Rhyfel Annibyniaeth America
 | 700434499000000000034,499
 | 7002483870000000000483.87 sq mi (70031253000000000001,253 km2) |  |
| Richland County
 | 139
 | Mansfield | 1 Mawrth, 1808 | Fairfield County | Saesneg am "dir ffrwythlon", disgrifiadol o dir yr ardal
 | 7005124475000000000124,475
 | 7002496880000000000496.88 sq mi (70031287000000000001,287 km2) |  |
| Ross County
 | 141
 | Chillicothe | 20 Awst, 1798 | Adams County a Washington County | NEnwyd er anrhydedd i'r Seneddwr yr Unol Daleithiau o Pennsylvania James Ross gan y llywodraethwr tiriogaethol Arthur St. Clair
 | 700478064000000000078,064
 | 7002688410000000000688.41 sq mi (70031783000000000001,783 km2) |  |
| Sandusky County
 | 143
 | Fremont | 1 Ebrill, 1820 | Huron County | Gair y llwyth Iroquoisam "ddŵr oer"
 | 700460944000000000060,944
 | 7002409180000000000409.18 sq mi (70031060000000000001,060 km2) |  |
| Scioto County
 | 145
 | Portsmouth | 1 Mai, 1803 | Adams County | Afon Scioto River; Scioto yw enw llwyth y Wyandot am "garw"
 | 700479499000000000079,499
 | 7002612270000000000612.27 sq mi (70031586000000000001,586 km2) |  |
| Seneca County
 | 147
 | Tiffin | 1 Ebrill, 1820 | Huron County | Llwyth brodorol y Seneca
 | 700456745000000000056,745
 | 7002550590000000000550.59 sq mi (70031426000000000001,426 km2) |  |
| Shelby County
 | 149
 | Sidney | 1 Ebrill, 1819 | Miami County | Y Cadfridog Isaac Shelby (1750–1826), swyddog yn Rhyfel Annibyniaeth America a Llywodraethwr Kentucky
 | 700449423000000000049,423
 | 7002409270000000000409.27 sq mi (70031060000000000001,060 km2) |  |
| Stark County
 | 151
 | Canton | 13 Chwefror, 1808 | Columbiana County | Y Cadfridog John Stark (1728–1822), swyddog yn Rhyfel Annibyniaeth America
 | 7005375586000000000375,586
 | 7002576140000000000576.14 sq mi (70031492000000000001,492 km2) |  |
| Summit County
 | 153
 | Akron | 3 Mawrth, 1840 | Medina County, Portage County a Stark County | Saesneg am "gopa"
 | 7005541781000000000541,781
 | 7002419380000000000419.38 sq mi (70031086000000000001,086 km2) |  |
| Trumbull County
 | 155
 | Warren | 10 Gorffennaf, 1800 | Jefferson County a Wayne County | Jonathan Trumbull (1710–1785), Llywodraethwr Connecticut pan drefnwyd y sir
 | 7005210312000000000210,312
 | 7002616480000000000616.48 sq mi (70031597000000000001,597 km2) |  |
| Tuscarawas County
 | 157
 | New Philadelphia | 15 Mawrth, 1808 | Muskingum County | Afon Tuscarawas, ar ôl y llwyth oedd yn byw ar lan yr afon
 | 700492582000000000092,582
 | 7002567580000000000567.58 sq mi (70031470000000000001,470 km2) |  |
| Union County
 | 159
 | Marysville | 1 Ebrill, 1820 | Delaware County, Franklin County, Logan County a Madison County | Saesneg am "undeb" y sir wedi ei ffurfio gan undeb o bedair sir
 | 700452300000000000052,300
 | 7002436650000000000436.65 sq mi (70031131000000000001,131 km2) |  |
| Van Wert County
 | 161
 | Van Wert | 1 Ebrill, 1820 | Darke County | Isaac Van Wart (1760–1828), cipiwr yr ysbïwr John André yn ystod Rhyfel Annibyniaeth America
 | 700428744000000000028,744
 | 7002410099999900000410.09 sq mi (70031062000000000001,062 km2) |  |
| Vinton County
 | 163
 | McArthur | 23 Mawrth, 1850 | Athens County, Gallia County, Hocking County, Jackson County a Ross County | Samuel Finley Vinton (1792-1862), Gwladweinydd o Ohio ac aelod o Gyngres yr UD
 | 700413435000000000013,435
 | 7002414080000000000414.08 sq mi (70031072000000000001,072 km2) |  |
| Warren County
 | 165
 | Lebanon | 1 Mai, 1803 | Hamilton County | Y Cadfridog Joseph Warren (1741–1775), swyddog yn Rhyfel Annibyniaeth America
 | 7005212693000000000212,693
 | 7002399630000000000399.63 sq mi (70031035000000000001,035 km2) |  |
| Washington County
 | 167
 | Marietta | 27 Gorffennaf, 1788 | Un o'r siroedd gwreiddiol | George Washington (1732–1799)
 | 700461778000000000061,778
 | 7002635150000000000635.15 sq mi (70031645000000000001,645 km2) |  |
| Wayne County
 | 169
 | Wooster | 1 Mawrth, 1808 | O dir heb ei drefnu | Y Cadfridog Anthony Wayne (1745–1796), swyddog yn Rhyfel Annibyniaeth America
 | 7005114520000000000114,520
 | 7002555360000000000555.36 sq mi (70031438000000000001,438 km2) |  |
| Williams County
 | 171
 | Bryan | 1 Ebrill, 1820 | Darke County | David Williams (1754–1831), cipiwr yr ysbïwr John André yn ystod Rhyfel Annibyniaeth America
 | 700437642000000000037,642
 | 7002421740000000000421.74 sq mi (70031092000000000001,092 km2) |  |
| Wood County
 | 173
 | Bowling Green | 1 Ebrill, 1820 | O dir heb ei drefnu | Eleazer D. Wood (1783–1814), sylfaenydd Fort Meigs
 | 7005125488000000000125,488
 | 7002617320000000000617.32 sq mi (70031599000000000001,599 km2) |  |
| Wyandot County
 | 175
 | Upper Sandusky | 3 Chwefror, 1845 | Marion County, Crawford County a Hardin County | ar ôl enw llwyth y Wyandot
 | 700422615000000000022,615
 | 7002405610000000000405.61 sq mi (70031051000000000001,051 km2) |  |

## Map dwysedd poblogaeth

Mae lliwiau gwahanol yn dynodi dwysedd trymach.

## Cyfeiriadau

 **Rhestrau o Siroedd  Unol Daleithiau yn ôl talaith**[cuddio]

 Alabama  **·**  Alaska  **·**  Arizona  **·**  Arkansas  **·**  Califfornia  **·**  Colorado  **·**  Connecticut  **·**  De Carolina  **·**  De Dakota  **·**  Delaware  **·**  Efrog Newydd  **·**  Florida  **·**  Georgia  **·**  Gogledd Carolina  **·**  Gogledd Dakota  **·**  Gorllewin Virginia  **·**  Hawaii  **·**  Idaho  **·**  Illinois  **·**  Indiana  **·**  Iowa  **·**  Kansas  **·**  Kentucky  **·**  Louisiana  **·**  Maine  **·**  Maryland  **·**  Massachusetts  **·**  Mecsico Newydd  **·**  Michigan  **·**  Minnesota  **·**  Mississippi  **·**  Missouri  **·**  Montana  **·**  Nebraska  **·**  Nevada  **·**  New Hampshire  **·**  New Jersey  **·**  Ohio  **·**  Oklahoma  **·**  Oregon  **·**  Pennsylvania  **·**  Rhode Island  **·**  Tennessee  **·**  Texas  **·**  Utah  **·**  Vermont  **·**  Virginia  **·**  Washington  **·**  Wisconsin  **·**  Wyoming  **·** Rhestr cyfansawdd o bob sir yn yr UD