Richmond, the county seat of Fort Bend County, is on the Brazos River fifteen miles southwest of Houston. The city's transportation links include U.S. highways 90A and 59, the Southern Pacific Railroad, and the Atchison, Topeka, and Santa Fe Railway. In early 1822 a group of twelve to fifteen men led by William W. Little camped in the vicinity of the present city and were soon followed by other members of Stephen F. Austin's Old Three Hundred. A log fort built at the bend in the Brazos River became the nucleus of a settlement, which came to be known as Fort Bend, or the "Fort Settlement." Fort Bend County has approximately 11 square miles of surface water in rivers, creeks and small lakes. The County is drained by the Brazos and San Bernard Rivers as well as Oyster Creek. The Brazos River formed a broad alluvial valley, up to ten miles wide in places. The resulting fertile soils have been a major contributing factor to the agricultural industry in the County. The three permanently floatable waterways in Fort Bend County are the Brazos River, the San Bernard River south of Farm to Market Road 442, and Oyster Creek south of State Highway 6. The San Bernard River south of Interstate Highway 10 is a seasonally floatable waterway, shared on the west with adjacent counties. Soils vary from the rich alluvial soils in the Brazos River Valley to sandy loam and clay on the prairies. Native trees include pecan, oak, ash and cottonwood, with some old bottomland forests remaining along waterways.