Legal sales of recreational marijuana in the United States nearly tripled between 2014 and 2015 — from $351 million to $998 million, according to research firms that track the marijuana industry. An additional $4.4 billion was spent on medical marijuana. Currently 26 states and the District of Columbia allow some form of marijuana use: 18 states have legalized medical marijuana, four allow medical and recreational use and four plus the District of Columbia have removed jail time for possessing small amounts. Both Democratic presidential nominee Hillary Clinton and Republican nominee Donald Trump support at least legalizing marijuana for medical use. Marijuana remains banned under federal law, and efforts to legalize it have been mixed. Federal courts this year dismissed a series of challenges against states that have legalized the drug. But Congress repeatedly has declined to overturn the federal ban.