As World War II erupted, many highway employees left to fight the war. The department’s 1940-1942 Biennial Report was dedicated “to those very fine young men who have left this department to go into the service of our country, and with the sincere hope that they will all return to resume their duties with the department as soon as the world is safe for decent-living people.”
In 1956, President Eisenhower signed the Federal Highway Act to build 41,000 miles of interstate highway across the nation. Nevada then had a pivotal role in completion of the interstate system when a new section of interstate in Lovelock was completed, eliminating the last traffic signal on Interstate 80 between the Pacific and Atlantic coasts.
While there had been no speed limit for decades, a speed limit law established lower speed zones on certain sections of highways in 1955.
In the 1960s, a hard hat and safety vest program was implemented; requiring NDOT employees to wear safety vests while working on the roadway.
The original Las Vegas Spaghetti Bowl was completed in 1968. The interchange connected Interstate 15 to the new, crosstown Las Vegas Expressway.