My Dad, who recently passed, was a huge sports fan from Chicago. He would have loved that map!
This one depends on users actually visiting the site...and it hasn’t been updated since 2010.
http://commoncensus.org/sports_map.php?sport=1
It has a much smaller sample size than facebook...the differences I see are:
Redskin support in Eastern North Carolina
Patriot support in upstate New York
Jets not completely dominated by the Giants
Raiders not completely dominated by 49ers near Oakland
(This may have changed with the rumors of them moving to LA)
Raider support near LA not in the CommonCensus map
)same rationale)
CommonCensus will leave area blank if they don’t get enough votes.