In the historic period, French and Spanish explorers encountered the
Bidai Indians, who were mentioned in Spanish records from 1691. Like other tribes, they suffered high fatalities from new infectious diseases caught from the Spanish and joined with the remnants of other Native American people later in the historic period. The area had very little settlement by Europeans or creole Spanish during the century of
Spanish colonial rule, but after Mexico gained its independence, it invited settlers from the United States to come to eastern Texas. They were allowed to practice their own religion, as long as they swore loyalty to the Mexican government. A few historic buildings in Anderson, such as the
Fanthorp Inn, date from this period, as well as some from the Republic of Texas and the early statehood years. So, the town and nearby area have been designated the Anderson Historic District, which is listed on the
National Register of Historic Places. Anglo-American migration to what became Grimes County began in the 1820s, when it was part of Mexico. Early settlers were primarily from the South, especially Alabama, and many brought enslaved African Americans with them to work the land. The first cotton gin in Texas was built by
Jared E. Groce, who arrived with 90 slaves and developed a cotton plantation near today's
Hempstead, Texas. In such conditions, Whites were anxious after the emancipation of slaves, and also struggled with adapting to a free labor market. White violence rose after the war, and the Ku Klux Klan established a local chapter in 1868 to assert dominance. Federal troops were stationed in the area and the Freedman's Bureau had an office in the county. They were not successful in protecting freedmen, but the bureau established schools in the area. The economy declined in the late 19th century, increasing social tensions. In 1859, the Houston and Texas Central extended its line into the county. Anderson, the county seat, rejected it and was bypassed for Navasota, which soon surpassed it in size. Anderson finally got a railroad in the early 1900s, but never caught up with Navasota. In the late 19th and 20th centuries, the
Burlington Northern Santa Fe and the
Union Pacific became the major railroads in the county. In response to the violence and takeover by the White Man's Union, African Americans began to leave the county in large numbers. The population of the county declined markedly from 1900 to 1920, and after 1930 to 1980. These were periods of the
Great Migration, as African Americans left Texas and other parts of the South to leave behind the oppression of
Jim Crow and
disenfranchisement, and seek better work. From 1940 on, many migrated to the West Coast for jobs in the expanding defense industry. Rural Whites also left the South for industrial cities. The county remained mostly rural and agricultural until the late 20th century, which contributed to its continuing population losses. Timber harvesting and processing were part of early industry in the 20th century, but livestock raising and dairy farms contributed more to the overall agricultural economy in the later 20th century, making up 93% of its revenues. In addition, crops have become more diversified. Railroad restructuring in the late 20th century resulted in mergers among some lines. In the 21st century, State Highway 90 is the major north–south thoroughfare, and State Highways 30 and 105 run east–west. With some new manufacturing, population began to increase since the late 1970s. In 2014, the census estimated 27,172 people living in Grimes County. About 59.5% were Anglo, 22.6% were Hispanic, and 16.5% were African American. ==Geography==