I'm sure you'll get a lot of different opinions on this. But now that DC is getting a stadium, NE & NYC share this distinction of worst stadium situations.
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This is where my thinking came from. RFK was a famous shithole, but it had history. Now they'll have a new stadium.
Gillette is really nice but it can take you 2.5 hours to get there from Boston and it's a straight up football stadium. Chicago Fire play an hour from where the people are. FC Dallas aren't really near Dallas. The Union are 30 minutes from Philly.
I would say Revs is the worst and we're second worst. I would then go Fire, Dallas, Columbus, Colorado.