See the context of this sign.

Old Route 66

Perhaps no other highway in the U. S. is as fabled as old
route 66. It has been immortalized in song, literature,
and even a T.V. series as the main street of America.
Automobiles came early to the desert, following the
railroad with its reliable water sources. In the early
1900s the route was known as the National Old Trails
Road. In 1926 it became U. S. Highway 66, and within a
decade was paved all the way from L. A. to Chicago.
Heavy travel by dustbowl emigrants led John Steinbeck
to label it the Mother Road. Chambless, where you now
stand, was a typical roadside stop. It was bypassed by
Interstate 40 in 1973, and the route 66 designation was
officially dropped in 1985.

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