Photo courtesy of Ron Wilbanks
These signs once graced Missouri highways, as Ron Wilbanks explains:
This was the standard size US marker for US Routes in Missouri from 1948 to 1973. The sign measures 42 cm x 40.5 cm in size and is made from .080" aluminum. The larger size 61 cm x 61 cm size markers were used as "Oversize" markers where greater visibility was desired or in conjunction with Interstate routes.