Title.
Exceptions include past demolitions for freeways, closures for through traffic, i.e. Broadway in NYC.
I'll nominate St. Louis. The grid remains solid, despite the construction of the major highways (44,55,64,and 70.) Now, traffic control on the other hand (STREET NOT THRU signs,and those god awful concrete blocks make me say "You can't get there from here") could be better.