It's no secret that support for legalization of marijuana has grown in the U.S. Poll after poll reflects this, including a Fox News survey conducted in January showing that 59% of Americans support legalization of marijuana -- an all-time high. 

That result, though, addressed only full legalization of marijuana. When asked about support for legalization of medical marijuana, the numbers increase significantly. The latest confirmation of this comes from a survey announced last week. You might be surprised who now broadly supports legal medical marijuana.

Marijuana buds on top of prescription form

Image source: Getty Images.

Survey says

AARP teamed up with the University of Michigan to conduct a survey of 2,007 Americans ages 50 to 80. The survey asked questions related to healthy aging and included several questions focused on medical marijuana.

So, what do older individuals think about medical marijuana? The AARP survey found that 80% either strongly or somewhat support use of marijuana with a physician's consent. That level is still lower than the overall U.S. population: A Quinnipiac survey in August 2017 found that 94% of American adults of all ages support legalization of medical marijuana. Still, it's clear that legalization of medical marijuana enjoys broad support within the older demographic.

It's not just a vague kind of support, either. When asked if they would either definitely or probably consider talking to their healthcare provider about medical marijuana if they had a condition that could respond to use of the drug, 70% of the AARP survey respondents stated that they would. Nearly as many participants in the survey -- 64% -- felt that the government should fund research to study the health effects of marijuana. 

Perhaps the most intriguing result of the survey was that 18% of respondents said that they personally knew someone who used medical marijuana. AARP's senior vice president of research, Alison Bryant, said that this number could represent "a tipping point" in support of legalized medical marijuana.

Only 6% of individuals surveyed responded that they used medical marijuana themselves. However, that's a higher level than found in prior studies of older adults. 

Potential implications

You might be tempted to dismiss yet another survey indicating increased support of legalization of medical marijuana. Past surveys haven't swayed enough members of Congress to pass legislation that decriminalizes medical use of the drug. Federal laws still prohibit any use of marijuana.

Could the AARP survey make a noticeable difference where others haven't? Maybe. Senators and congressional representatives know that older Americans get out and vote. In the 2016 national election, for example, 45% of the electorate was age 50 or older. 

A detailed analysis of the 2016 election found that more than 70% of Americans ages 65 and older voted. Around 67% of the next highest-demographic group, individuals ages 45 to 64, turned out for the election. By comparison, only 46% of Americans between the ages of 18 and 29 voted. 

In the past, it was easy for politicians to write off support for marijuana legalization as more skewed toward the younger generation. That's no longer the case. And when an AARP survey finds 80% of Americans who are highly likely to vote in support of something, it wouldn't be surprising if more elected officials start to change their tune.

This probably won't mean a major shift in the political dynamics in Washington in the immediate future, though. It will probably take a while for the effect of broader support among older Americans to influence legislators.

But it's not just senators and congressional reps who pay attention to polls -- and especially pay attention to the AARP. Federal agency heads also know that they must watch the weathervane to see which way the political winds are blowing. The recent AARP survey results could even lower the likelihood that Attorney General Jeff Sessions will direct the Department of Justice to go after states that have legalized medical marijuana.

Investors' dilemma

Some investors might look at the increasing support for legalized marijuana in the U.S. and want to capitalize on the trend. These investors face a dilemma, though: There aren't many good investing alternatives. They also still face the risk that the Trump Administration could crack down on marijuana businesses despite increased public support.

Probably the best stock for investors to consider as a way to profit from the expansion of the marijuana industry in the U.S. is Scotts Miracle-Gro (SMG 0.86%). The company provides many of the critical supplies needed by marijuana growers, including hydroponics and lighting systems.

However, Scotts stock has fallen more than 20% year to date because of weakness in its subsidiary that caters to the marijuana industry. The primary issue appears to be California's slowness in finalizing regulatory policies related to the state's legalization of recreational use of marijuana. Scotts could continue to struggle until all of the regulations are firmly in place. 

Some Canadian marijuana growers established U.S. operations, notably including Aphria (NASDAQOTH: APHQF). Because marijuana remains illegal at the federal level in the U.S., though, the Toronto Stock Exchange threatened to delist the stocks of companies with a significant presence in the U.S. marijuana market. That prompted Aphria to scale back its U.S. ties.

Looking north to Canada is still the best bet for marijuana investors. The country already allows legal use of medical marijuana and appears to be on track to legalize recreational marijuana later this year. But the AARP survey hints at the possibility of future changes in U.S. marijuana laws. If so, it could be the baby boomer generation that creates the biggest boom for the marijuana industry.