Tennessee-native Thomas Calvin Weir (1826-1901) came to Williamson County in 1856, bought land in this area, and became a prosperous farmer. Alabaman James Francis Towns (1850-1937) arrived in 1870 and settled nearby on the San Gabriel River, where he and his brother, Robert W. Towns (1848-1938), operated a gin, blacksmith shop, and Towns' Mill. In the late 19th century, the communities of Weir and Townsville, or Towns’ Mill, grew around these early settlers. Local churches included Baptist and Presbyterian congregations that met at the Prairie Springs School, as well as an African American church that met in a school near Mankins Crossing. Calvin Weir’s daughter Lucy served as postmaster at the Townsville post office and also ran a small store there. The two communities developed similarly until 1893, when the Georgetown and Granger Railroad came through Weir and bypassed Townsville. In 1903, after the Missouri, Kansas and Texas Railroad, known as the Katy, bought the line, most area residents moved into Weir, which was officially established that same year. The Katy Lake Resort, created by the railroad on the river at Towns' Mill Dam, drew tourists to the area. The Townsville post office moved to Weir, and with several new businesses the town began to thrive. A flood in 1913 damaged the resort and several local businesses, and after a severe drought, World War I, and the Great Depression, Weir’s population declined before beginning to prosper again in the mid-20th century. Following voter approval, Weir incorporated as a city in 1987.