Stillwater finally went over 50,000 in population but it's probably not much of a surprise that lots of cities in Oklahoma are having difficulty holding their own, including Tulsa. At least still growing Tulsa suburbs make up for that.

https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=bkmk

Tulsa is a just a poorly run city simple as that. They have the potential to be the next Austin/Asheville in the middle of that based on what I’ve seen. Perhaps the overly conservative nature of the city holds it back.