While Jefferson Parish completed its section of the route between West End and Kenner in the early 1930s , several factors caused the construction of the remaining link between Kenner and Frenier to be abandoned soon afterward . The route through the LaBranche swamp in St. Charles Parish proved to be the most difficult road construction in the state up to that time , and the heavy expenditure invested became a continual source of controversy . The highway 's practical need was questioned as construction progressed on the more important Airline Highway , a streamlined route between New Orleans and Baton Rouge that would parallel the lakeshore route through the area . The death knell , however , was the construction of the Bonnet Carré Spillway in 1933 that bisected the route . A two-mile section of the embankment , not yet surfaced for travel , was severed to provide a path for floodwaters as part of a larger system designed to prevent a re-occurrence of the Great Mississippi Flood of 1927 . With three highways — the existing Jefferson Highway , the new Airline Highway , and the proposed Lakeshore Highway — now potentially requiring bridges to cross the spillway , the Lakeshore Highway could no longer be provided for . As a result , the section of the route through Jefferson Parish was scarcely used and only sporadically maintained for automobile traffic
Great Mississippi Flood of 1927
Great Mississippi Flood of 1927
U.S. Route 51 in Louisiana