What is the latest show that had its entire in run b/w? The earliest entirely in color?
I am sure someone here can do a better job than I of answering the OP, however:
If you consider “Walt Disney Presents” and “Walt Disney’s Wonderful World of Color” to be different shows rather than just different names for the same show, then perhaps we are getting close to at least one of your answers.
“Walt Disney’s Wonderful World of Color” began in the fall (I think) of 1961, and the opening segments were always in color, although some of the material may have been black and white.
“Walt Disney Presents” probably ended at the end of the summer in 1961. We didn’t have a color TV then, so I don’t know if anything shown on that show was in color.
IMDb considers both of the above just to be new names for the “Disneyland” TV series, so they would say that my answer would have to be wrong. However, 1961 would be close to the first year that color broadcasting became widely used.
I had thought that “The Adventures of Superman” or “The Cisco Kid” might qualify as the first shows made all in color, since the producers cleverly filmed them in color, correctly figuring that the reruns would be more valuable that way when color TV became common, but apparently, the first two years of Superman and some episodes of Cisco were filmed in black and white.