DENVER — Three-fourths of Americans say it’s inevitable that marijuana will be legal for recreational use across the nation, whether they support such policies or not, according to a public opinion poll released Wednesday.

The Pew Research Center survey also shows increased support for ending mandatory minimum prison sentences for non-violent drug offenders and doing away altogether with jail time for small amounts of pot.

The opinions come as public debate on these topics has led lawmakers around the nation to consider policy changes.

Since California became the first state to legalize medical marijuana in 1996, at least 19 others, including Maine, and the District of Columbia have followed suit, including two that have approved recreational use. More than a dozen state legislatures have considered legalization measures this year, and a recreational-use referendum is expected to be on the Maine statewide ballot in 2016.

The telephone survey found that 75 percent of respondents – including majorities of both supporters and opponents of legal marijuana – think that the sale and use of pot eventually will be legal nationwide.

The survey indicates that four years ago, 52 percent of respondents said they thought the use of marijuana should not be legal, while 41 percent said it should. The new poll shows a reversal, with 54 percent in favor of legalization and 42 percent opposed. It marked a turning point in a gap that has been shrinking fairly steadily since 1969, the earliest data available, when 84 percent said pot should be illegal and only 12 percent thought otherwise.

“Pot just doesn’t seem as bad,” said Gregory Carlson, a 52-year-old landscaper from Denver who did not participate in the Pew survey.

The survey also highlighted a dramatic shift in attitudes on drug conviction penalties.

The survey was about evenly divided in 2001 on whether it was good or bad for states to move away from mandatory minimum sentences for non-violent drug offenders. Today, poll respondents favored moving away from such policies by a nearly 2-to-1 margin, or 63 percent to 32 percent.