From the 1958 annual report of the Missouri Highway Commission, David Backlin contributes an early example of an Interstate sign assembly. Later, of course, US 66 was decommissioned in Missouri and other states, although there is still a Missouri 66 in Jasper County, including Joplin. In addition, historic markers for US 66 have been placed along the former route of the famous highway.
Image courtesy of David Backlin