John Seabrook Sydnor and son John Barrett Sydnor were auctioneers and commission merchants in Houston and Galveston (John Seabrook was mayor of Galveston from 1846-1847 and also a slave dealer in Galveston in the 1850s). Seabrook Sydnor, another son of John Seabrook, worked for them in the 1860s and later founded the city of Seabrook TX in 1903.

Sydnor street in Houston once ran north from Buffalo Bayou to Lyons St. (then Odin St.) but now runs north off and onto Lyons from Richardson St. In Seabrook there is a small stretch of Sydnor St. left just north of NASA Rd. 1 between 4th St. and Highway 146, and in Galveston Sydnor Lane runs along Sydnor Bayou at the Moody Gardens Golf Course.

c. 1870s: