About 10-15 years ago I read that mule deer numbers were in decline. Some thought it might be the expansion of the white tail. I believed it cause I worked for a guy that went to Wyoming for mulies and didn't see one so they shot white tails. Are mulie numbers on decline?

Colorado has 375,000 mule deer, and 10,000 whitetails. We're not a state known for whitetails though.

Compared to Texas that has 3-4 million whitetails.

There are a lot more areas out West where the mule deer are declining for a lot of different reasons than increasing, that's for sure. Whitetails are so much more adaptable to many types of habitat compared to mulies that it's ridiculous.