was any tunnel constructed here?
Yes, the construction of the Mule Pass Tunnel
U.S. Route 80 in Arizona
By far the largest combined roadway improvement project on US 80 in the 1950s was the construction of the Mule Pass Tunnel and adjoining bypass of downtown 
which places do u.s. route 80 in arizona connect? From the California border in Yuma to the New Mexico state line near Lordsburg. when was it started? November 11, 1926
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U.S. Route 80 in Arizona [SEP] Construction of the Mule Pass Tunnel
The tunnel crew exceeded their own record twice by September, first increasing to of material excavated per day, then further to of material per day. By October 6, over of tunnel had been excavated. The width of the tunnel was now wide, exceeding the original proposed width. The tunnel also measured in height at an elevation of above sea level. As the tunnel was excavated, the bore was supported by multiple steel reinforcing beams.