A majority of Americans support the legalization of marijuana for the first time in four decades of polling, according to Pew Research. Legalizing the drug — which has already happened in two states, while it has been decriminalized in 14 others — is supported by 52 percent of Americans; 45 percent would like to continue the federal prohibition against cannabis.

The shift in public attitudes seems closely tied to the public’s growing weariness with imprisoning people for nonviolent drug crimes, with 72 percent saying that government efforts to enforce marijuana laws cost more than they are worth.

The percentage of Americans who see smoking marijuana as a “moral” issue has flipped since 2006. Then 50 percent said use of the drug was a moral issue. Today the same percentage say otherwise. This could be the effect of many seeing the so-called “War on Drugs” as more immoral than drug use itself.

Another key factor in the country’s growing tolerance for the drug is Baby Boomers supporting legalization at even greater numbers than they did in the 1970s.

The generational divide on the drug — and the most overwhelming evidence that the cultural shift on marijuana will be permanent — comes from the answers to the question, “Have you ever happened to try marijuana in the past year?”

Majorities of Americans 18-64 said that they had, while only 22 percent of those over 65 had used the drug in the past year.

States that have legalized the drug for medical use or decriminalized its use are more in favor of legalization, which seems to make an argument for the state-by-state effort reformers have been making to loosen drug laws.

Michelle Alexander’s book, The New Jim Crow: How the War on Drugs Gave Birth to a Permanent American Undercaste, makes the case against ending the drug war as a continuation of the civil rights movement.

Russ Belville, Outreach Coordinator for the National Organization for the Reform of Marijuana Laws, wrote, “The War on Drugs is primarily a War on Marijuana, which makes up 49.8% of all drug war arrests, 89% of those arrests for simple possession.”

Alexander makes the case that the millions of generally law-abiding Americans like Barack Obama who have admitted using marijuana help move the culture toward a system that seeks to treat drug abuse, instead of punishing it. This poll shows that those who have used the drug are less likely to want to waste government resources on punishing others who have done so.

Photo: “it was 3 a.m.” via Flickr.com