U.S. Highway 136 (US 136) is a short U.S. Highway in Keokuk, Iowa. The route was designated nationally in 1951 and has remained largely unchanged through Keokuk since then. The highway originally crossed the Mississippi on the Keokuk Rail Bridge, which was the second bridge built and operated by Andrew Carnegie's Keokuk & Hamilton Bridge Company in that location. While it was designed for wagons and early automobiles, crossing the rail bridge became difficult in larger modern vehicles, specifically semi trucks. As a result, a new automobile-only bridge was built directly to the south of the older span. The Keokuk–Hamilton Bridge opened in 1985 eight months early and under budget.