In contrast, voters have reacted negatively to gun control proposals, even after horrific events like the Newtown massacre. That was apparent in the Senate's rejection of the Toomey-Manchin gun registration bill.
What about the cultural issue that most pundits mention first, abortion? Attitudes have remained roughly the same: Most Americans think abortion should be, in Bill Clinton's phrase, safe, legal and rare.
Young Americans, contrary to their libertarian leaning on same-sex marriage, are slightly less pro-abortion rights than their elders. They've seen sonograms, and all of them by definition owe their existence to a decision not to abort.
And from the point of view of the unborn child, abortion is the opposite of liberating.
Back in the conformist America of the 1950s -- a nation of greater income equality and stronger labor unions, as liberals like to point out -- marijuana, homosexual acts and abortion weren't political issues. They were crimes. And opposition to gun control measures in the 1950s and 1960s was much less widespread and vigorous than it is today.
Is this libertarian trend a good thing for the nation? Your answer will depend on your values.
I'm inclined to look favorably on it. I think the large majority of Americans can use marijuana and guns responsibly. Same-sex marriage can be seen as liberating, but it also includes an element of restraint. Abortions in fact have become more rare over a generation.
But I do see something to worry about. In his bestseller "Coming Apart," my American Enterprise Institute colleague Charles Murray shows that college-educated Americans have handled liberating trends of the 1970s like no-fault divorce with self-restraint.
But at the bottom of the social scale we have seen an unraveling, with out-of-wedlock births, continuing joblessness, lack of social connectedness and civic involvement.
In conformist America the old prohibitions provided these people with guardrails, as The Wall Street Journal's Daniel Henninger has written. In today's more libertarian America, the guardrails may be gone.