This is my last post on our Route 66 adventure in Missouri. 1941 marked the beginning of construction on the brand new 4-lane version of Route 66 in Missouri. The older 2-lane section wound around hills and through valleys while the new highway cut through the hills and leveled out the road (to some extent)! The 4-lane highway came at the same time as construction of Fort Leonard Wood in central Missouri. The new highway would provide an ample roadway for travel to and from the Army base. The new bridge over the Big Piney River crosses the river about a mile north of the 1926 bridge. Ultimately, this highway section saw millions of people who traveled between Illinois and California until Interstate 44 opened in the 1970s.