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 that highlights shifting attitudes following the drug war era and tough-on-crime legislation.
The Pew Research Center survey also shows increased support for ending mandatory minimum prison sentences for nonviolent drug offenders and doing away altogether with jail time for small amounts of marijuana.
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 and the District of Columbia have followed suit, including two that have approved recreational use. More than a dozen state legislatures considered legalization measures this year.
Meanwhile, critics and political leaders, both liberal and conservative, have clamored for an end to harsh drug sentences, saying mandatory minimums have contributed to prison overcrowding, civil rights violations, and strained budgets. US Attorney General Eric Holder has been pushing Congress to overhaul drug sentencing policies.
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.
It was the first time that question had been asked, but it reflects a gradual trend of acceptance.
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.
Respondents said by a ratio greater than 3-to-1 that people who use small amounts of pot should not go to jail.
‘‘Even people who don’t favor the legalization of marijuana think the possession of small amounts shouldn’t result in jail time,’’ said Carroll Doherty, Pew’s Director of Political Research.
The nation thought differently a generation ago.
Congress passed the Anti-Drug Abuse Act in 1986 to set mandatory minimum sentences for federal drug crimes that could end up in life sentences for repeat offenders.
Years later, many states reported prisons bursting at the seams, prompting public officials to start abandoning ‘‘lock ’em up’’ drug policies in the 1990s. The trend has since accelerated.
Last month, Holder testified in support of proposed sentence reductions in an effort to reserve ‘‘the harshest penalties for the most serious drug offenders.’’
Such plans, including one drafted by Senator Rand Paul, Republican of Kentucky, that would give judges wider discretion in sentencing have picked up support from both Republicans and Democrats.
The poll suggested that, despite shifting attitudes on legalization, the public remains concerned about drug abuse, with 32 percent of those surveyed calling it a crisis and 55 percent of respondents viewing it as a serious national problem.