To provide employment during the Great Depression, relief work camps operated from late 1932 to 1935, by which time the highway was almost complete.

[1] When Legg had earlier examined the proposed customs site on an uncompleted section of road, he discovered the surveyed route would create an unsatisfactory uphill grade to the boundary.

At then the highest elevation in Canada for a customs office, snow covered the ground when it opened in a tent in May 1936.

[3] The highway was built over 13 months between the fall of 1934 and the summer of 1936 by Montana state employees and contractors.

[1] The Chief Mountain Border Station and Quarters, constructed in 1939, was added to the National Register of Historic Places on May 20, 2008.