The increased military traffic along US 66 during World War II and the consequent extreme demands put on the road bed caused parts of the road to be replaced along this stretch during the 1940s. This stretch of US 66 became a four-lane road with two lanes in each direction; the new lanes became the southbound lanes. For south of Litchfield, the southbound lanes still carry two-way traffic. A new alignment of Route 66 headed northeast of Hamel through Livingston. This new section bypassed Mount Olive to the northeast, later running west of the old route through Litchfield before rejoining the original path. Sections of the older alternate route were destroyed during the 1930s when Lake Springfield was created; the fragments of the old route that remain were added to the National Register of Historic Places on May 12, 2009.