Up Close on Baseball's Borders - The New York Times
Top 50 Metro Areas in the U.S. Have 31 NFL Teams
High School Football America Top 100 National Rankings, NFL Play Football
National Football League - Wikipedia
NFL Fan Map: Favorite Team by County
Ranking the most popular NFL teams by state
Where Do NFL Fans Live? Mapping Football Fandom Across the U.S. - Priceonomics
40 maps and charts that explain sports in America - Vox
The Most Popular NFL Teams by County, State
Where Do NFL Fans Live? Mapping Football Fandom Across the U.S. - Priceonomics
Which Football Team Is Most Popular in New Jersey? - New Jersey Digest