Thomas County, in the northwestern corner of the state, is located in the second tier south of Nebraska and the second east from Colorado. It is bounded on the north by Rawlins county; on the east by Sheridan; on the south by Gove and Logan, and on the west by Sherman. It was created in 1873 and named in honor of George H. Thomas, a major-general of the Civil war. The boundaries were defined as follows: "Commencing at the point where the east line of range 31 west crosses the 1st standard parallel; thence south with said line to the 2nd standard parallel; thence west with said standard parallel to the east line of range 37 west; thence north with said range line to the 1st standard parallel; thence east with said standard parallel to the place of beginning."

In 1881 before the county was organized a man by the name of T. D. Hamilton, who was hunting with a small party within the boundaries of the county, discovered a cave full of human skeletons. The men were following a wounded wolf which took refuge in the cave. On exploring it they found the cave to be a sepulcher of a prehistoric race. The interior consisted of two chambers with perpendicular walls hewn out of the rock. Weapons and other relics were found with the bones of the dead. The bodies were in various positions, some standing, some sitting and some lying. A passage way had been chiseled out and far in the interior was a stream of water. At one point in the cave a single sound would produce a score of echoes.

Among the first settlers were, J. R. Colby, J. W. Irwin, who became the first postmaster at Colby, H. W. Miller, James Auld, Dr. D. M. Dunn and E. P. Worchester. In Jan., 1885, there were but 161 inhabitants in the county. On March 12 the Thomas County Cat (sometimes called the Thomas Cat) was established by Worchester and Dunn and printed at the sod house of H. W. Miller at Colby. It was the first paper published in the county, though the next week another paper was started by Brown & Son and printed at the residence of J. R. Colby, the man in whose honor the town was named. Settlers came in by the hundreds during that year and by the end of the summer the residents petitioned for a separate county organization. W. G. Porter was appointed census taker. The returns were made early in October and showed a population of 1,900 of whom 777 were householders. Gov. Martin issued the proclamation organizing the county on Oct. 8. Colby was named as the temporary county seat and the following officers were appointed: county clerk, Samuel Stewardson; commissioners, B. F. Heaston, W. H. Kingery and E. A. Crouse. The election to complete the organization was held on Nov. 17. Colby was chosen county seat with only 13 opposing votes, and the following officers were elected: County clerk, James N. Fike; treasurer, N. D. Bean; sheriff, W. H. Kingery; clerk of the district court, Edward J. Paine; register of deeds, J. W. Irwin; attorney, William G. Porter; probate judge, M. L. Lacey; superintendent of public instruction, W. W. Walker; surveyor, T. P. Chambers; coroner, M. McGreevy; commissioners, Frank Pingree, M. W. Witham and R. T. Hemming. W. H. Copeland was the first representative.

In Sept., 1887, the first railroad reached Colby, and by Jan., 1888, the three lines which now run to the town had been built. A branch of the Union Pacific from Salina enters in the east and crosses west to Colby where it terminates. Another branch of the same road, diverging from the main line at Oakley in Logan county, enters in the south and crosses northwest to Colby. The Chicago, Rock Island & Pacific enters in the northeast and crosses southwest to Colby, thence west into Sherman county. There are 76 miles of railroad.

The county is divided into 10 townships, viz: Barrett, Hale, Kingery, Lacey, Menlo, Morgan, Randall, Revohl, Smith, Summers and Wendell. The postoffices are Brewster, Colby, Gem, Halford, Kingery, Levant, Menlo, Mingo and Rexford. The population in Dec., 1885, was reported as 2,500. In 1890 it was 5,538. In the next 10 years there was a decrease to 4,112, but during the next decade there was a substantial increase, the population in 1910 being 5,455. The assessed valuation of property in that year was $12,957,739. The average wealth per capita is $2,374, which is more than $700 in excess of the average wealth per capita for the state.

The general surface is undulating prairie with bluffs and rough lands along the streams. The native timber is limited to clumps of cottonwood trees. Bottom lands are not extensive. Sandstone is found in several localities. The Saline river has its source in the southwest and flows east across the southern tier of townships. The south fork of the Solomon flows east across the county, somewhat south of the center, and the north fork of the same river has its source in the west and flows northeast into Sheridan county. The north and south forks of Sappa creek and Prairie Dog creek enter in the west and flow northeast, the two former into Rawlins and the latter into Sheridan county.

The number of acres under cultivation in 1888 was 90,000. In that year 81,895 pounds of butter and 1,225 pounds of cheese were marketed. In 1910 dairy products were worth $53,000; animals sold for slaughter, $63,289; poultry and eggs, $32,000; wheat, the principal crop, $475,627; barley, nearly $150,000; corn, $84,233; sorghum, $81,000; hay, $45,063. The total value of farm products was $1,089,541. The number of head of live stock was 19,677, worth $1,282,822. The number of acres of land under cultivation was 335,017, less than half the total area.