History of U.S. Route 40
Present day U.S. Route 40 runs from Atlantic City, NJ to Park City, UT. In its past the eastern terminus has been in Cumberland (now Baltimore), MD, New York, NY, and Atlantic City. The western terminus was found in Vandalia, IL, Los Angeles, CA, San Francisco, CA, and Park City, UT.The National Road
It originally started with the National Road. This was one of the United States earliest highway projects. At that time the idea was to connect east coast to the Ohio River in order to provide an easy means of travel. Originally started in 1806, construction of the National Road progressed westward until it reached the goal at the Ohio River. At that time it was decided to further extend the highway into Ohio, Indiana, Illinois, and Missouri. The goal then being to reach Jefferson City, MO on the Mississippi River by way of Saint Louis Unfortunately funding for the project ran out in 1839 and The National Road was considered complete in Vandalia, Illinois.
The National Old Trails Coast-to-Coast Highway
Shortly after The National Road was complete, it was rolled into the National Old Trails Coast-To-Coast Highway. This road was started in 1912, and reached from New York, NY to Los Angeles, CA. Along this route, the National Society of the Daughters of the American Revolution erected large statues in each state though which this highway passed. Known as "Madonna of the Trail," these were placed to mark the trail when their plan to place 3,095 individual mile markers failed.
U.S. Route 40
Once again as time passed the route changed again. In 1926 the route was realigned to run from Atlantic City, NJ to San Francisco, CA. It was then renamed to U.S. Route 40. Originally it was going to be called U.S. Route 1, however it would not have followed the established highway naming conventions. East/west transcontinental highways use multiples of 10, and north/south highways use numbers ending in five. Between 1926 and today several different realignments have taken place, including alternates US40N and US40S running through Kansas and Colorado. Today far western portions of U.S. Route 40 have been decommissioned placing the official end of the highway in Park City, UT.
By no means is this an exhaustive list of Waymarks that can be included, however here are a few examples of what could be added.
Milestones
Madonna of the Trail
Historical Markers pertaining to the history of US Route 40 and its predecessors
Note: It's impossible to read at this size, but the second historical marker mentions that the accident took place on The National Road