So…? Arlington and Fairfax are different counties than DC. Heck, they’re in a different state and across a river too. But nobody would argue they aren’t suburb

So…? Arlington and Fairfax are different counties than DC. Heck, they’re in a different state and across a river too. But nobody would argue they aren’t suburbs of DC. 25 miles is well within commuting distance for many major metro areas. Boulder may arguably be a suburb or not. But an arbitrary 25 mile limit isn’t what defines suburb or not.