I did student teaching at a high school a mile and a half away from the high school I attended just outside Chicago. I remember the students (mostly Mexican-American) mocking how I said “root” (and other oo-words) where I use the short o͝o sound rather than the long o͞o sound of, e.g., boot. Everyone I grew up with (except my Mom who was born in Western Pennsylvania), pronounces these words the same as I do, but the changes in the demographics of the area (from mostly Slavs, Italians and some Greeks and Serbs to mostly Latino) have also changed the micro-regional accent as well.
It is interesting to note that Barack Obama, despite his cosmopolitan upbringing, has acquired the Chicago habit of truncating a lot of vowels to schwas so he will, for example, say “tuh” for “to.” Then again, I’ve picked up a lot of L.A. regionalisms in my own speech thanks to living there for 18 years of my life (the most notable is saying freeway rather than expressway).