According to the poll issued by research company Gallup on Thursday, this is the highest rate recorded in relative since 1996. US public support for same-sex marriage has more than doubled over the past two decades, Xinhua news agency reported.
When Gallup first polled on the issue in 1996, only 27 percent said such marriages should be recognised by the law.
Majority support was recorded for the first time in 2011, and the percentage has since been growing, Gallup found.
Attitudes towards gay marriage have been shifting since Gallup started measuring them. This has taken place across all age groups, with each demographic subgroup demonstrating greater acceptance this year.
Support for gay marriage has consistently been highest among adults younger than 30 years, but support declines with each step up the age scale.
This year marks the first time in Gallup’s trend that the majority of adults aged 65 and older said gay marriage should be legal. Fifty-three percent of Americans aged 65 and older now support same-sex marriage.
That is still well below the 83 percent support among 18- to 29-year-olds, the highest support among the age groups, the poll added.