Center for American Progress has issued a report which looks at polls and demonstrates that the majority of the country supports marriage equality. Crosby Burns and Ben Harris write,
In short, marriage equality is now a mainstream American value. Just a decade ago, however, a majority of Americans opposed laws and policies that extended marital rights to same-sex couples. In the ensuing 10 years, the United States has come a long way with states passing marriage equality legislation, national leaders coming out in support of equal relationship recognition rights, and same-sex couples sharing their stories of love and commitment with their friends and family.
And here is an infographic of the support for marriage equality: