Sealy was founded by the Gulf, Colorado and Santa Fe Railway in 1875 and named for the President of the railroad, George Sealy, as it built north from Galveston toward Brenham. The railroad established yards and a roundhouse, and in 1880, a Post Office was granted. In 1882, the Texas Western, a narrow gauge railroad, entered Sealy from the east. Direct connections could not be made because the Santa Fe railway was standard gauge and within a few years, the Texas Western went into receivership.
In 1892, the Missouri-Kansas-Texas ("Katy") Railroad crossed the Santa Fe in Sealy as it constructed its main line into Houston from Waco. In 1900, the Cane Belt RR built into Sealy from Eagle Lake, and this line was eventually acquired by the Santa Fe. Today, the Santa Fe line remains heavily used by BNSF. UP now owns the Katy line which has been severed further east. As a result, there is little traffic east of Sealy. Virtually all UP traffic through Sealy uses the Santa Fe line to or from the UP main line at Rosenberg to the south (see Tower 17). The Cane Belt line to Eagle Lake has been abandoned although tracks remain in place as far south as Interstate 10.