With the start of the new year, Illinois became the second state in the Midwest to allow recreational marijuana sales.

Illinois, where the legislature and governor passed a law to legalize marijuana in 2019, let stores start selling marijuana for recreational purposes on January 1, 2020. According to the Chicago Tribune, 37 marijuana stores in the state were licensed and able to open with the start of 2020.

In Illinois, anyone age 21 or older can purchase and possess marijuana. The state is licensing retailers and others along the supply line — although, as in other states, local jurisdictions can opt out of sales. About 40 local jurisdictions have done so, according to the Tribune.

Lt. Gov. Juliana Stratton (D) was among the first to buy marijuana this week, purchasing pot gummies at a Chicago store.

Meanwhile, Gov. JB Pritzker (D), who signed the legalization law, granted more than 11,000 pardons for low-level marijuana offenses on December 31 — fulfilling a promise that the new law would stop not just future marijuana arrests and convictions but undo previous ones as well.

Illinois previously allowed the use and sale of marijuana for medical purposes.

Illinois was the second state in the Midwest to legalize, following Michigan, where sales for recreational use began in December. Nine other states and Washington, DC, have legalized marijuana, although one of those states, Vermont, and DC don’t allow sales for recreational use.

Supporters of legalization argue that it eliminates the harms of marijuana prohibition: the hundreds of thousands of arrests around the US, the racial disparities underlying those arrests, and the billions of dollars that flow from the black market for illicit marijuana to drug cartels that then use the money for violent operations around the world. All of this, legalization advocates say, will outweigh any of the potential downsides — such as increased cannabis use — that might come with legalization.

Opponents, however, claim that legalization will enable a huge marijuana industry that will market the drug irresponsibly. They point to America’s experiences with the alcohol and tobacco industries in particular, which have built their financial empires, in large part, on some of the heaviest consumers of their products. This could result in more people using pot, even if it leads to negative health consequences.

For more on the legalization of marijuana, read Vox’s explainer.