It's been quite the night for marijuana in several ballot measures across the country.

Voters in Washington state and Colorado appear to have voted "yes" on measures that would legalize the sale of pot to adults, without the need for a doctor's prescription. (The final votes are still being counted.) And earlier Tuesday evening, voters in Massachusetts overwhelmingly approved the measure to allow the use of medical marijuana.

Oregon voters have to decide on a similar measure to those passed in Washington and Colorado, which would allow marijuana use for any individual over the age of 21, but it appears to have been defeated.

Arkansas's medical marijuana initiative also appears to have been defeated.

Montana, which already has a medical marijuana law, is voting on whether or not to restrict patient access in the state.

So far, states that have approved medical marijuana have walked a fine line with federal laws that still prohibit the sale of marijuana under any circumstances. The full legalization of marijuana in these two states is expected to increase that tension between local and federal laws.

In total, six states are considering marijuana initiatives.

"Now that this law has been passed [in Massachusetts], it will finally be legal and safe for myself and many others in the state to procure the medicine," Eric McCoy, 59, told the Boston Globe.

NBC News reports that 17 states and the District of Columbia already have laws allowing for the medical use of marijuana, according to the National Council of Legislatures.