To the list of issues that divide the country along partisan lines, you can add an unusual item: football.

Yes, virtually every slice of America still watches football in enormous numbers. But blue America — particularly the highly educated Democratic-leaning areas of major metropolitan areas — is increasingly deciding that it doesn’t want its sons playing football.

The number of boys playing high school football has fallen 15 percent over the last six years in both Minnesota and Wisconsin, according to the National Federation of State High School Associations. The decline in Colorado has been 14 percent. It has been 8 percent in Massachusetts and Maryland, 7 percent in New York and 4 percent in California.

Each of these states voted Democratic in the last two presidential elections, and each is among the more educated states in the nation, measured by the share of the population with a bachelor’s degree.