Marijuana could be legal for medical or recreational use in 29 U.S. states after the November election.
The issue will be put to voters in nine states, with legalization backers enjoying well-funded campaigns and polls showing a high likelihood that they will prevail in the most populous states.
Currently, marijuana is allowed for medical use in 26 states. Florida, Arkansas and North Dakota could join their ranks. Montana voters are deciding whether to loosen its current regulations on medical marijuana.
In addition, California, Arizona, Nevada, Massachusetts and Maine — all of which already allow medical use — could join Oregon, Colorado,...