The United States on Monday celebrates the second anniversary of Obergefell vs. Hodges.

Decided on June 26, 2015, the Supreme Court's Obergefell ruling found that gay and lesbian couples have a constitutional right to marry.

In one sweeping motion, the 5-4 decision struck down state bans that excluded gay couples from marriage.

Conservatives criticized the ruling, with many politicians vowing to undermine such unions. In Mississippi, for example, lawmakers approved a law that protects opponents of marriage equality. President Donald Trump has said that he would sign a similar bill introduced by Republicans.

(Related: Appeals court lifts hold on Mississippi's HB1523, dubbed nation's worst anti-LGBT law.)

According to a recent Gallup survey, roughly 10 percent of LGBT Americans are married to a spouse of the same sex. Older adults are also more likely to marry than younger adults.

(Related: Poll: More than 10% of American LGBT adults married to same-sex spouse.)

Doug Warner and Truman Smith married last year, nearly 15 years to the day after they met while vacationing in Greece. A quote from the case written by Justice Anthony Kennedy was included in the back of their wedding program. “Rising from the most basic human needs, marriage is essential to our most profound hopes and aspirations.”