The United States is gradually becoming the land of the red, white, and green.

Michigan on Tuesday became the tenth state to legalize marijuana after voters passed Proposition 1, making it the first Midwestern state to legalize the drug.

Four states voted on marijuana legalization measures in Tuesday's midterm elections. Voters in Utah and Missouri also passed initiatives to legalize medical marijuana, though an initiative in North Dakota failed.

Marijuana legalization is sweeping the US: In June, Oklahoma voted to legalize medical marijuana, joining the number of other states that already have medical marijuana laws on the books.

In January, Vermont became the first state to legalize marijuana through the legislature, rather than a ballot initiative, when the governor signed the bill into law.

Support for the drug reached new highs in 2018. A Gallup poll showed that 64% of Americans favor legalization, and even a majority of Republicans back it.

Ten states and Washington, DC have now legalized marijuana for recreational use for adults over the age of 21. And 33 states have legalized medical marijuana.

Here's a summary of where Americans can legally light up — no doctor's letter required — in 2018.

Read more: Top cannabis VCs give their best advice on how to invest in the booming marijuana industry

Melia Robinson contributed to an earlier version of this post.