In the original Louisiana Highway system in use between 1921 and 1955, LA 76 was part of several different routes, including State Route 998 along Bayou Maringouin; State Route 142 to Rosedale; State Route 1 and State Route 7 to Lobdell Highway; and State Route 30 into Port Allen. The section between Rosedale and Port Allen had formerly been part of one of the state's most important highways, the Jefferson Highway auto trail, which was the main traffic route between New Orleans, Baton Rouge, and Shreveport in the days before the numbered U.S. Highway system. It became part of the original alignment of US 71 in 1926 and then US 190 in 1935 when the latter was extended west from Baton Rouge. This portion of what is now LA 76 connected to the Baton Rouge ferry across the Mississippi River before the completion of the Huey P. Long Bridge upstream on the current alignment of US 190 in 1940. This and other highway realignments in the area caused the Rosedale Road to decline in importance in the years leading up to the Louisiana Department of Highways' renumbering of the state highway system in 1955.