Hearne is on the Missouri Pacific and the Southern Pacific railroads, U.S. highways 79 and 190, and State Highway 6, twelve miles southwest of Franklin and nine miles south of Calvert in southwestern Robertson County. It is on land originally granted to Francisco Ruiz, Mexican commander of Fort Tenoxtitlán in 1830. In the 1840s Code Brown operated a tavern and stage stop in the area. Passengers traveling between Houston and Port Sullivan stopped there for refreshments, and the tavern functioned as the local post office and general store. During the 1850s Robertson County grew rapidly. The Hearnes, gentlemen planters of the Old South, moved in 1852 to the region, where they acquired 10,000 acres. There they operated large cotton plantations. In 1858 Christopher C. Hearne, determined to construct a railroad through the county, offered railroad promoters right-of-way and townsite land. However, the Civil War erupted before the railroad reached Hearne's plantation, and work halted. Eventually, Hearne's widow deeded 700 acres to the Houston and Texas Central Railway. Railroad construction resumed in 1867 and finally arrived at the new Hearne depot in April 1868. Soon large homes, a hotel, general stores, several saloons (initially housed in tents), and a drugstore lined the streets of Hearne. Soon thereafter churches organized, a Masonic hall was built, and Daniel Brady established a cotton gin. A post office opened in 1869. In 1870 the International-Great Northern negotiated a right-of-way across Robertson County on an east-west axis. The two lines intersected at Hearne. The cotton gins and two railroads established Hearne as the regional center for cotton marketing. The town incorporated in 1871 and in 1885 had four churches, schools, two gristmill-cotton gins, two hotels, and a newspaper, the Hearne Enterprise. The Hearne Democrat was published by J. Felton Lane in 1911.
The population grew from 1,300 in 1885 to 2,129 by 1900 and 3,511 in 1940. German prisoners of war were housed at a camp built just west of the Hearne city limits in 1942. The camp housed up to 8,000 men, and the first prisoners arrived early in 1943. The facility closed in 1946. By the 1960s Hearne had an airstrip and businesses involved in manufacturing and agricultural industries. In 1991 it had a factory that manufactured steel tanks and cotton gin machinery, a vitreous sanitary ware plant, an oil mill, and a door factory. In addition, the town served as a terminal for the distribution of petroleum products, operated dehydration facilities, and was a regional center for the marketing of cotton and other agricultural products. The population in 1990 was 5,132; in 2000 it was 4,690.