Illinois on Tuesday officially became the 11th U.S. state to legalize recreational marijuana.

Gov. J.B. Pritzker signed into a law a bill that legalizes the possession, purchase and sale of cannabis and allows for the expungement of low-level cannabis convictions. The law will take effect Jan. 1.

"I'm so proud that our state is leading with equity and justice in its approach to cannabis legalization and its regulatory framework," Pritzker tweeted. "Signing this bill into law won't undo the injustices of the past or make whole the lives that were interrupted. We can't turn back the clock – but we can turn the page."

Illinois is the first state to legalize recreational marijuana sales through legislation, a process that has proved tricky even in states with Democrat-controlled statehouses that have been more receptive to changing drug laws. Legalization efforts in New York and New Jersey fizzed this year despite support from top lawmakers.

The measure passed the Illinois legislature late last month, just hours before the end of the year's legislative session.

It allows residents over the age of 21 to possess 30 grams of marijuana and sets up a regulated retail scheme. It also contains provisions aimed at helping cannabis start-ups owned by residents of areas disproportionately affected by cannabis prohibition and those with marijuana convictions.

Prtizker, a Democrat, campaigned on the issue and his election boosted an existing effort for legalization in the state.

