State Highway 42 is a state highway located in the northeastern portion of the Texas in Gregg and Rusk counties. This route was designated in 1962 over former SH 259.

SH 42 was originally proposed in 1919 as a route from Greenville to Marshall. By 1933, the route was readjusted, with the northwest terminus extended north to Wright, while the southeast portion was cancelled or transferred to SH 155. By 1938, the entire remaining route had been transferred to U.S. Highway 69.