Damnation Alley (1977) on Netflix

In the aftermath of a nuclear holocaust a group of survivors, mostly US Air Force personnel, travel from the western US to Albany, New York from where a radio broadcast has been received. Led by a no nonsense Major, Eugene Denton, they travel in specialized vehicles built specifically for survival in harsh conditions. Along the way, they are joined by an attractive young woman when they stop in Las Vegas, are joined by a young boy when they meet desperate survivors in the desert, must face hoards of killer cockroaches and survive a major flood in Detroit.