| County |
Year Formed | Parent County(s) | County Seat |
Area (sq. mi.) |
| Anderson | 1846 | Houston | Palestine | 1,077 |
| Andrews | 1875 | Bexar | Andrews | 1,501 |
| Angelina | 1846 | Nacogdoches | Lufkin | 807 |
| Aransas | 1871 | Refugio | Rockport | 280 |
| Archer | 1858 | Fannin | Archer City | 907 |
| Armstrong | 1876 | Bexar | Clause | 910 |
| Atascosa | 1856 | Bexar | Jourdanton | 1,218 |
| Austin | 1837 | Old Mexican Municipality | Bellville | 656 |
| Bailey | 1876 | Bexar | Muleshoe | 827 |
| Bandera | 1856 | Uvalde, Bexar | Bandera | 793 |
| Bastrop | 1836 | Old Mexican Municipality | Bastrop | 895 |
| Baylor | 1858 | Fannin | Seymour | 862 |
| Bee | 1857 | Goliad, Refugio, Live Oak, San Patricio | Beeville | 880 |
| Bell | 1850 | Milam | Belton | 1,055 |
| Bexar | 1836 | Old Mexican Municipality | San Antonio | 1,248 |
| Blanco | 1858 | Gillespie, Comal, Burnet, Hays | Johnson City | 714 |
| Borden | 1876 | Bexar | Gail | 900 |
| Bosque | 1854 | McLennan, Milam | Meridian | 989 |
| Bowie | 1840 | Red River | New Boston | 891 |
| Brazoria | 1836 | Old Mexican Municipality | Angleton | 1,407 |
| Brazos | 1841 | Washington, Robertson | Bryan | 588 |
| Brewster | 1887 | Presidio | Alpine | 6,169 |
| Briscoe | 1876 | Bexar | Silverton | 887 |
| Brooks | 1911 | Starr, Zapata, Hidalgo | Falfurrias | 942 |
| Brown | 1856 | Travis, Comanche | Brownwood | 936 |
| Burleson | 1846 | Milam, Washington | Caldwell | 668 |
| Burnet | 1852 | Travis, Bell, Williamson | Burnet | 994 |
| Caldwell | 1848 | Gonzales | Lockhart | 546 |
| Calhoun | 1846 | Victoria, Matagorda, Jackson | Port Lavaca | 540 |
| Callahan | 1858 | Bexar, Travis, Bosque | Baird | 899 |
| Cameron | 1848 | Nueces | Brownsville | 905 |
| Camp | 1874 | Upshur | Pittsburg | 203 |
| Carson | 1876 | Bexar | Panhandle | 924 |
| Cass | 1846 | Bowie | Linden | 937 |
| Castro | 1876 | Bexar | Dimmitt | 899 |
| Chambers | 1858 | Jefferson, Liberty | Anahuac | 616 |
| Cherokee | 1846 | Nacogdoches | Rusk | 1,052 |
| Childress | 1876 | Bexar, Youngland District | Childress | 707 |
| Clay | 1857 | Cooke | Henrietta | 1,085 |
| Cochran | 1876 | Bexar | Morton | 775 |
| Coke | 1889 | Tom Green | Robert Lee | 908 |
| Coleman | 1858 | Travis, Brown | Coleman | 1,277 |
| Collin | 1846 | Fannin | McKinney | 851 |
| Collingsworth | 1876 | Bexar, Youngland District | Wellington | 909 |
| Colorado | 1837 | Old Mexican Municipality | Columbus | 964 |
| Comal | 1846 | Bexar, Gonzales, Travis | New Braunfels | 555 |
| Comanche | 1856 | Bosque, Coryell | Comanche | 930 |
| Concho | 1858 | Bexar | Paint Rock | 992 |
| Cooke | 1848 | Fannin | Gainesville | 893 |
| Coryell | 1854 | Bell | Gatesville | 1,057 |
| Cottle | 1876 | Fannin | Puducah | 2,800 |
| Crane | 1887 | Tom Green | Crane | 782 |
| Crockett | 1875 | Bexar | Ozona | 2,806 |
| Crosby | 1876 | Bexar | Crosbyton | 898 |
| Culberson | 1911 | El Paso | Van Horn | 3,815 |
| Dallam | 1876 | Bexar | Dalhart | 1,505 |
| Dallas | 1846 | Nacogdoches, Robertson | Dallas | 880 |
| Dawson | 1876 | Bexar | Lamesa | 903 |
| Deaf Smith | 1876 | Bexar | Hereford | 1,497 |
| Delta | 1870 | Hopkins, Lamar | Cooper | 278 |
| Denton | 1846 | Fannin | Denton | 911 |
| De Witt | 1846 | Goliad, Gonzales, Victoria | Cuero | 910 |
| Dickens | 1876 | Bexar | Dickens | 907 |
| Dimmit | 1858 | Uvalde, Bexar, Maverick, Webb | Carrizo Springs | 1,307 |
| Donley | 1881 | Jack | Clarendon | 929 |
| Duval | 1858 | Live Oak, Starr, Nueces | San Diego | 1,795 |
| Eastland | 1858 | Bosque, Coryell, Travis | Eastland | 924 |
| Ector | 1887 | Tom Green | Odessa | 903 |
| Edwards | 1858 | Bexar | Rocksprings | 2,120 |
| Ellis | 1850 | Navarro | Waxahachie | 939 |
| El Paso | 1849 | Bexar | El Paso | 1,014 |
| Erath | 1856 | Bosque, Coryell | Stephenville | 1,080 |
| Falls | 1850 | Limestone, Milam | Marlin | 770 |
| Fannin | 1837 | Red River | Bonham | 895 |
| Fayette | 1837 | Bastrop, Colorado | La Grange | 950 |
| Fisher | 1876 | Bexar | Roby | 897 |
| Floyd | 1876 | Bexar | Floydada | 992 |
| Foard | 1891 | Hardeman, Knox, King, Cottle | Crowell | 703 |
| Fort Bend | 1837 | Austin | Richmond | 876 |
| Franklin | 1875 | Titus | Mount Vernon | 294 |
| Freestone | 1850 | Limestone | Fairfield | 888 |
| Frio | 1858 | Atascosa, Bexar, Uvalde | Pearsall | 1,133 |
| Gaines | 1876 | Bexar | Seminole | 1,504 |
| Galveston | 1838 | Brazoria | Galveston | 399 |
| Garza | 1876 | Bexar | Post | 895 |
| Gillespie | 1848 | Bexar | Fredericksburg | 1,061 |
| Glasscock | 1887 | Tom Green | Garden City | 900 |
| Goliad | 1836 | Old Mexican Municipality | Goliad | 859 |
| Gonzales | 1836 | Old Mexican Municipality | Gonzales | 1,068 |
| Gray | 1876 | Bexar | Pampa | 921 |
| Grayson | 1846 | Fannin | Sherman | 934 |
| Gregg | 1873 | Rusk, Upshur | Longview | 273 |
| Grimes | 1846 | Montgomery | Anderson | 799 |
| Guadalupe | 1846 | Bexar, Gonzales | Seguin | 713 |
| Hale | 1876 | Bexar | Plainview | 1,005 |
| Hall | 1876 | Bexar, Young | Memphis | 876 |
| Hamilton | 1842 | Bosque, Comanche, Lampasas, Coryell | Hamilton | 836 |
| Hansford | 1876 | Bexar, Young | Spearman | 921 |
| Hardeman | 1858 | Fannin | Quanah | 688 |
| Hardin | 1858 | Jefferson, Liberty | Kountze | 898 |
| Harris | 1836 | Harrisburg Municipality | Houston | 1,734 |
| Harrison | 1839 | Shelby | Marshall | 908 |
| Hartley | 1876 | Bexar, Young | Channing | 1,462 |
| Haskell | 1858 | Fannin, Milam | Haskell | 901 |
| Hays | 1848 | Travis | San Marcos | 678 |
| Hemphill | 1876 | Bexar, Young | Canadian | 903 |
| Henderson | 1846 | Houston, Nacogdoches | Athens | 888 |
| Hidalgo | 1852 | Cameron | Edinburg | 1,569 |
| Hill | 1853 | Navarro | Hillsboro | 968 |
| Hockley | 1876 | Bexar, Young | Levelland | 908 |
| Hood | 1865 | Johnson | Granbury | 425 |
| Hopkins | 1846 | Lamar, Nacogdoches | Sulphur Springs | 789 |
| Houston | 1837 | Nacogdoches | Crockett | 1,234 |
| Howard | 1876 | Bexar, Young | Big Spring | 901 |
| Hudspeth | 1917 | El Paso | Sierra Blanca | 4,566 |
| Hunt | 1846 | Fannin, Nacogdoches | Greenville | 840 |
| Hutchinson | 1876 | Bexar | Stinnett | 871 |
| Irion | 1881 | Tom Green | Mertzon | 1,052 |
| Jack | 1856 | Cooke | Jacksboro | 920 |
| Jackson | 1836 | Old Mexican Municipality | Edna | 844 |
| Jasper | 1836 | Old Mexican Municipality | Jasper | 921 |
| Jeff Davis | 1887 | Presidio | Fort Davis | 2,258 |
| Jefferson | 1836 | Old Mexican Municipality | Veaumont | 937 |
| Jim Hogg | 1913 | Brooks, Duval | Hebbronville | 1,136 |
| Jim Wells | 1911 | Nueces | Alice | 867 |
| Johnson | 1854 | Ellis, Hill, Navarro | Cleburne | 731 |
| Jones | 1858 | Bexar, Bosque | Anson | 931 |
| Karnes | 1854 | Bexar | Karnes City | 753 |
| Kaufman | 1848 | Henderson | Kaugman | 788 |
| Kendall | 1862 | Derr, Blanco | Boerne | 663 |
| Kenedy | 1921 | Willacy, Hidalgo, Cameron | Sarita | 1,389 |
| Kent | 1876 | Bexar, Young | Jayton | 878 |
| Kerr | 1856 | Bexar | Kerrville | 1,107 |
| Kimble | 1858 | Bexar | Junction | 1,250 |
| King | 1876 | Bexar | Guthrie | 914 |
| Kinney | 1850 | Bexar | Brackettville | 1,359 |
| Kleberg | 1917 | Nueces | Kingsville | 853 |
| Knox | 1858 | Young, Bexar | Benjamin | 845 |
| Lamar | 1840 | Red River | Paris | 919 |
| Lamb | 1876 | Bexar | Littlefield | 1,013 |
| Lampasas | 1856 | Bell, Travis | Lampasas | 714 |
| La Salle | 1858 | Bexar, Webb | Cotulla | 1,517 |
| Lavaca | 1846 | Colorado, Victoria, Jackson, Gonzales | Halletsville | 971 |
| Lee | 1874 | Bastrop, Burleson, Washington, Fayette | Giddings | 631 |
| Leon | 1846 | Robertson | Centerville | 1,078 |
| Liberty | 1836 | Old Mexican Municipality | Liberty | 1,174 |
| Limestone | 1846 | Robertson | Groesbeck | 931 |
| Lipscomb | 1876 | Bexar | Lipscomb | 933 |
| Live Oak | 1856 | Nueces, San Patricio | George West | 1,057 |
| Llano | 1856 | Bexar | Llano | 939 |
| Loving | 1887 | Tom Green | Mantone | 671 |
| Lubbock | 1876 | Bexar, Crosby | Lubbock | 900 |
| Lynn | 1876 | Bexar | Tahoka | 888 |
| McCulloch | 1856 | Bexar | Brady | 1,071 |
| McLennan | 1856 | Milam | Waco | 1,031 |
| McMullen | 1858 | Bexar, Live Oak, Atascosa | Tilden | 1,163 |
| Madison | 1854 | Leon, Grimes, Walker | Madisonville | 473 |
| Marion | 1860 | Cass | Jefferson | 385 |
| Martin | 1876 | Bexar | Stanton | 914 |
| Mason | 1858 | Gillespie | Mason | 934 |
| Matagorda | 1836 | Old Mexican Municipality | Bay City | 1,127 |
| Maverick | 1856 | Kenedy | Eagle Pass | 1,287 |
| Medina | 1848 | Bexar | Hondo | 1,331 |
| Menard | 1858 | Bexar | Menard | 902 |
| Midland | 1885 | Tom Green | Midland | 902 |
| Milam | 1836 | Old Mexican Municipality | Cameron | 1,019 |
| Mills | 1887 | Comanche, Brown, Hamilton, Lampasas | Goldthwaite | 748 |
| Mitchell | 1878 | Bexar | Colroado City | 912 |
| Montague | 1857 | Cooke | Montague | 928 |
| Montgomery | 1837 | Washington | Conroe | 1,047 |
| Moore | 1876 | Bexar | Dumas | 905 |
| Morris | 1875 | Titus | Daingerfield | 256 |
| Motley | 1876 | Bexar | Matador | 959 |
| Nacogdoches | 1836 | Old Mexican Municipality | Nacogdocges | 939 |
| Navarro | 1846 | Robertson | Corsicana | 1,068 |
| Newton | 1846 | Jasper | Newton | 935 |
| Nolan | 1881 | Young, Bexar | Sweetwater | 915 |
| Nueces | 1846 | San Patricio | Corpus Christi | 847 |
| Ochiltree | 1876 | Bexar | Perryton | 919 |
| Oldham | 1876 | Bexar | Vega | 1,485 |
| Orange | 1852 | Jefferson | Orange | 362 |
| Palo Pinto | 1856 | Navarro, Bosque | Palo Pinto | 949 |
| Panola | 1846 | Harrison, Shelby | Carthage | 812 |
| Parker | 1855 | Bosque, Navarro | Weatherford | 902 |
| Parmer | 1876 | Bexar | Farwell | 885 |
| Pecos | 1871 | Presidio | Fort Stockton | 4,776 |
| Polk | 1846 | Liberty | Livingston | 1,061 |
| Potter | 1876 | Bexar | Amarillo | 902 |
| Presidio | 1852 | Bexar | Marfa | 3,857 |
| Rains | 1870 | Hopkins, Hunt, Wood | Emory | 243 |
| Randall | 1876 | Bexar | Canyon | 917 |
| Reagan | 1903 | Tom Green | Big Lake | 1,173 |
| Real | 1913 | Bandera, Kerr, Edwards | Leakey | 697 |
| Red River | 1836 | Old Mexican Municipality | Clarksville | 1,054 |
| Reeves | 1883 | Pecos | Pecos | 2,626 |
| Refugio | 1836 | Old Mexican Municipality | Refugio | 771 |
| Roberts | 1876 | Bexar | Miami | 915 |
| Robertson | 1837 | Milam | Franklin | 864 |
| Rockwall | 1873 | Kaufman | Rockwall | 128 |
| Runnels | 1858 | Bexar, Travis | Ballinger | 1,056 |
| Rusk | 1843 | Nacogdoches | Henderson | 932 |
| Sabine | 1836 | Old Mexican Municipality | Hemphill | 486 |
| San Augustine | 1836 | Old Mexican Municipality | San Augustine | 524 |
| San Jacinto | 1870 | Liverty, Polk, Montgomery, Walker | Coldspring | 572 |
| San Patricio | 1836 | Old Mexican Municipality | Sinton | 693 |
| San Saba | 1856 | Bexar | San Saba | 1,136 |
| Schleicher | 1887 | Crockett | Eldorado | 1,309 |
| Scurry | 1876 | Bexar | Snyder | 900 |
| Shackelford | 1858 | Bosque | Albany | 915 |
| Shelby | 1836 | Old Mexican Municipality | Center | 791 |
| Sherman | 1876 | Bexar | Stratford | 923 |
| Smith | 1846 | Nacogdoches | Tyler | 932 |
| Somervell | 1875 | Hood, Johnson | Glen Rose | 188 |
| Starr | 1848 | Nueces | Rio Grande City | 1,226 |
| Stephens | 1858 | Bosque | Breckenridge | 894 |
| Sterling | 1841 | Tom Green | Sterling City | 923 |
| Stonewall | 1876 | Bexar | Aspermont | 925 |
| Sutton | 1840 | Crockett | Sonora | 1,455 |
| Swisher | 1876 | Bexar, Young | Tulia | 902 |
| Tarrant | 1849 | Navarro | Fort Worth | 868 |
| Taylor | 1858 | Bexar, Travis | Abilene | 917 |
| Terrell | 1905 | Pecos | Sanderson | 2,357 |
| Terry | 1876 | Bexar | Brownfield | 886 |
| Throckmorton | 1858 | Fannin | Throckmorton | 912 |
| Titus | 1846 | Red River, Bowie | Mount Pleasant | 412 |
| Tom Green | 1874 | Bexar | San Angelo | 1,515 |
| Travis | 1840 | Bastrop | Austin | 989 |
| Trinity | 1850 | Houston | Groveton | 692 |
| Tyler | 1846 | Liberty | Woodville | 922 |
| Upshur | 1846 | Harrison, Nacogdoches | Gilmer | 587 |
| Upton | 1867 | Tom Green | Rankin | 1,243 |
| Uvalde | 1850 | Bexar | Uvalde | 1,564 |
| Val Verde | 1885 | Crockett, Kinney, Pecos | Del Rio | 3,150 |
| Van Zandt | 1848 | Henderson | Canton | 855 |
| Victoria | 1836 | Old Mexican Municipality | Victoria | 887 |
| Walker | 1846 | Montgomery | Huntsville | 786 |
| Waller | 1873 | Austin, Grimes | Hempstead | 514 |
| Ward | 1887 | Tom Green | Monahans | 836 |
| Washington | 1836 | Texas Municipality | Brenham | 610 |
| Webb | 1848 | Bexar | Laredo | 3,363 |
| Wharton | 1846 | Matagorda, Jackson | Wharton | 1,086 |
| Wheeler | 1876 | Bexar, Young | Wheeler | 905 |
| Wichita | 1858 | Youngland District | Wichita Falls | 606 |
| Wilbarger | 1858 | Bexar | Vernon | 947 |
| Willacy | 1911 | Hidalgo, Cameron | Raymondville | 589 |
| Williamson | 1848 | Milam | Georgetown | 1,137 |
| Wilson | 1860 | Bexar, Karnes | Floresville | 807 |
| Winkler | 1887 | Tom Green | Kermit | 840 |
| Wise | 1856 | Cooke | Decatur | 902 |
| Wood | 1850 | Van Zandt | Quitman | 689 |
| Yoakum | 1876 | Bexar | Plains | 800 |
| Young | 1856 | Bosque, Fannin | Graham | 919 |
| Zapata | 1858 | Starr, Webb | Zapata | 999 |
| Zavala | 1858 | Uvalde, Maverick | Crystal City | 1,298 |