Where I am it's a very Rural area, the mayor funds the police department which is much less than New York, but we do mostly have 03 - 08 Crown Vics, They we're donated from an neighbouring county back in 2011.
The last transition/replacing of cars by the department itself was 2004, at that time the department still ran an Aspen near the town hall. They had to push to start it.
I said above about what the oldest car in my department and to my research it's not that unique.
Many departments I have contacted whom gave me information still have older cars, The NOPD for example still had 97 Crown Vic's the last I heard. Kansas City KS still had a 1985 Caprice until 08, I heard from some that they may still have 9C1's still patrolling.
Some departments in Alaska, (Sitka) most notably still have Caprice's as reserves and 97 Crown Vic's and in ND one department has an 87 Crown Vic still in Use. I read a blog of someone whom took a picture in 2009 of a cop in an 1983 Caprice in ND. Western Montana a few departments still have 97 Crown Vic's that are patrolling.
Furthermore In New Jersey, the state with many counties, Newark, Ocean Beach are some of the counties that still use 97 Crown Vic's and Im pretty sure in Newark One detective car is an 9C1 Caprice. But that was in 2017 so it could have changed.
I went up to Maine in 2016 an I saw a few 9C1 Caprice's Parked in Front of an department with a few 95 - 97 Crown Vic's as well. Government Fleet is a good website to start off some research on the topic.
Honolulu, Hawaii in 2015 Bought more cars to replace some of their fleet in which has not been upgraded since 2005, many of the cars were still 95 - 97 Crown Vic's.
Departments in Texas have been older Cars as well some of them still run 97 Crown Vic's I heard in the Rural parts. One department had to resort buying an Uber used car for their fleet. It had 320k miles on it.
People whole live in those areas are more Happy to correct me on that.