Route 66 was a spin-off of Naked City. The Naked City episode "Four Sweet Corners" (1959) served as a backdoor pilot of sorts for the series Route 66, created by Stirling Silliphant. Route 66 ran on CBS from 1960 to 1964, and, like Naked City, followed the "semi-anthology" format of building the stories around the guest stars, rather than the regular cast
Never knew!!! I probably have seen most of both!