Dallam County is located in the far northwestern corner of the Texas Panhandle bordering New Mexico to the west, and Oklahoma to the north. The county seat is Dalhart. Located in the rolling grasslands of the Panhandle, the terrain is marked by numerous dry arroyos and by the intermittent Rita Blanca, Carrizo, and Coldwater creeks, all of which drain into the Canadian River. Ranching, the county's dominant industry, utilizes abundant grasses to produce large numbers of beef cattle, along with some hogs and horses.

Until white settlement reached it in the 1870s the Dallam County region existed as just a small portion of the huge, vacant High Plains that stretch from Texas to Canada. The earliest Plains Apache inhabitants were followed by the nomadic Comanches and Kiowas in their quest for buffalo and booty.

Dallam County was named for James W. Dallam, Republic of Texas lawyer and newspaper editor. On January 10, 1882, the Capitol Freehold Land and Investment Company received approximately two-thirds of the county as part of its famous XIT Ranch holdings. Buffalo Springs, in the northern part of the county, served as the first headquarters of the XIT. Between 1882 and 1887 only XIT cowboys and a few other settlers occupied the county. In 1887 and 1888 the Fort Worth and Denver City Railway was built through the county as it extended its line from Amarillo into New Mexico and Colorado. On May 14, 1888, the road reached Texline, the railroad's choice of a new division point. Perico, twelve miles southeast, began as a shipping point for the XIT. By 1890 the population of the county had reached 112. In 1891 the county was organized with Texline as its seat. Organization led to the county's first election, in which John V. Farwell was chosen county judge and H. Willis, T. H. Hardin, J. L. Baughn, and J. B. Stevens county commissioners.

In 1900 and 1901 the Chicago, Rock Island and Pacific Railroad, building from Enid, Oklahoma, and Tucumcari, New Mexico, crossed Dallam County. A settlement soon developed at the point where the Rock Island crossed the Fort Worth and Denver. The town, named Dalhart because it is in both Dallam and Hartley counties, developed around the Rock Island shops and roundhouse built in 1901. Dalhart prospered, and as a result of an election held in 1903 it became the county seat. Conlen, in the eastern part of the county, was founded on the Rock Island line that year. Later, in 1931, the town of Kerrick was laid out on the North Plains and Santa Fe line, which ran through the county's northeast corner from Stratford to Boise City, Oklahoma.

Ranching dominated the Dallam County economy in its early years. The few jobs not dependent on ranching were tied to the local railroads. However, in the first two decades of the twentieth century farmers began making their way into the county. Whereas only four farms, comprising 1,280 acres total, existed in the county in 1900, 210 farms covering more than 48,000 acres were producing by 1910. The large ranches had been broken up by then, and extensive land sales continued into the 1920s. By the mid-1930s over one-third of the county was classified as cropland. The primary crop, wheat, was supplemented by such grains as corn, milo, and millet. The Great Depression and Dust Bowl dealt harshly with Dallam County's economy, yet the ranchers and farmers pulled through. From the 1940s on, the farm and ranch economy grew and prospered.

The Dalhart Texan is the county's sole newspaper, and the chief cultural event is the annual XIT Reunion and Rodeo, held at Dalhart in August. Lake Rita Blanca, just across the line in Hartley County, provides recreation. Rita Blanca National Grassland covers several hundred acres in the north central part of the county.

The county has a total area of 1,505 square miles, of which 1,503 square miles is land and 2 square miles (0.1%) is water. The population recorded in the 1890 Federal Census was 112 and peaked at 7,830 in 1930. The 2010 census recorded 6,703 residents in the county.

Neighboring counties are Cimarron County, Oklahoma (north), Sherman County, Texas (east), Hartley County, Texas (south), Union County, New Mexico (west), and Moore County, Texas (southeast). The county seat is Dalhart. Other communities in the county include Texline, Perico, Buffalo Springs, Conlen, Kerrick, Coldwater, Ware, and Chamberlin.

Birth Records - The Texas Department of State Health Services has records from 1903 to present. Records for the last 75 years considered private and will only be provided to certain individuals. To obtain current information on who may obtain a record, how to submit a request and an official request form, see the Texas Department of State Health Services website or write to Texas Vital Records, Department of State Health Services, P.O. Box 12040, Austin, TX 78711-2040.

For older birth records you will have to write to the County Clerk of the applicable county. The existence of birth records prior to 1903 will vary widely from county to county. Local historical societies and genealogy collections in local libraries may be able to provide some information.

Death Records - The Texas Department of State Health Services has records from 1903 to present. Records for the last 25 years considered private and will only be provided to certain individuals. To obtain current information on who may obtain a record, how to submit a request and an official request form, see the Texas Department of State Health Services website or write to Texas Vital Records, Department of State Health Services, P.O. Box 12040, Austin, TX 78711-2040.

Marriage Records - The Texas Department of State Health Services can provide a verification letter of marriage for Texas marriages from 1966 to present. This is NOT a marriage license. To obtain a certified copy of a marriage license you must contact the County or District Clerk in the county or district where the marriage took place.

Local historical societies and genealogy collections in local libraries may be able to provide some information.

Divorce Records - The Texas Department of State Health Services can provide a verification letter of divorce for Texas divorces from 1968 to present. This is NOT a copy of the divorce decree. To obtain a certified copy of a copy of the divorce decree you must contact the County or District Clerk in the county or district where the divorce took place.

Local historical societies and genealogy collections in local libraries may be able to provide some information.