The marijuana debate has come a long way since “Reefer Madness.”

While the Michael Phelps incident has brought the recreational use of pot back into the spotlight, much of the news about the drug in recent years has focused on whether it should be legalized for medical purposes, primarily to reduce pain for cancer victims.

In a new Rasmussen Reports national telephone survey, Americans are closely divided on the question of whether marijuana should be legalized: 40% say it should be, while 46% disagree. Fourteen percent (14%) are not sure which course is better.

(Want a free daily e-mail update? Sign up now. If it's in the news, it's in our polls.)

Nearly half of men (48%) say pot should be legal in this country, but just 34% of women agree. The plurality of women (49%) oppose legalization.

Americans under the age of 40 are much more supportive of legalizing the drug than are older Americans.

Sixty percent (60%) of Republicans are opposed to the legalization of marijuana. Democrats are more evenly split on the question, giving legalization the edge by five points.

This partisan divide is clear in a commentary by Froma Harrop highlighting President Obama’s support for decriminalization earlier in his political career and his choice of former Seattle Police Chief Gil Kerlikowske as his drug czar. Ms. Harrop, a columnist for the Providence Journal, says Kerlikowske “presided over a city that had virtually decriminalized small-scale possession of marijuana,” while John Walters, his predecessor during the Bush years, was much more of a hard-line drug enforcer.

Among adults not affiliated with either major political party, 49% favor legalization of marijuana, while 41% oppose it.

Perhaps indicative of lessening public opposition to marijuana are the findings in a survey about the Phelps incident in which the Olympic superstar was photographed smoking the drug at a party. Sixty percent (60%) of Americans still regard Phelps favorably, but most also think Kellogg’s made the right decision to drop him as a celebrity endorser on cereal boxes.

The World Health Organization estimates that 42% of Americans have tried marijuana, the highest usage level in the 17 countries it profiled. Some researchers contend that marijuana is the number one cash crop in the United States.

Three Nobel Prize winners including Milton Friedman were among the more than 500 economists who endorsed a 2005 Harvard study that concluded that legalization of marijuana “would save $7.7 billion per year in state and federal expenditures on prohibition enforcement and produce tax revenues of at least $2.4 billion annually if marijuana were taxed like most consumer goods. If, however, marijuana were taxed similarly to alcohol or tobacco, it might generate as much as $6.2 billion annually.”

Opponents of legalization argue that marijuana is harmful to health and has a “gateway effect,” encouraging use of harder and more dangerous drugs. Drug Enforcement Administration officials say some marijuana growers are part of larger international drug organizations who export violence and harder drugs into the country.

Several states, including Alaska, California and Maryland, allow limited marijuana use for medical purposes, but the drug is still illegal nationwide under federal law.

Please sign up for the Rasmussen Reports daily e-mail update (it’s free)… let us keep you up to date with the latest public opinion news.

See survey questions and toplines. Crosstabs are available to Premium Members only.