SPRINGFIELD, Ill. — Illinois' new governor delivered on a top campaign promise Tuesday by signing legislation legalizing small amounts of marijuana for recreational use, making the state the 11th to do so and the first to implement a statewide cannabis marketplace designed by legislators.

Legalization in Illinois also means that nearly 800,000 people with criminal records for purchasing or possessing 30 grams of marijuana or less may have those records expunged, a provision minority lawmakers and interest groups demanded. It also gives cannabis-vendor preference to minority owners and promises 25 percent of tax revenue from marijuana sales to redevelop impoverished communities.

Gov. J.B. Pritzker, whose election last year gave Democrats complete control over state government again after four years under GOP predecessor Bruce Rauner, signed the bill in Chicago amid a bevy of lawmakers and pot proponents.

Under the measure, residents can purchase and possess up to 1 ounce (30 grams) of marijuana at a time. Nonresidents could have up to 15 grams. The law provides for cannabis purchases by adults 21 and older at approved dispensaries, which, after they're licensed and established, may start selling Jan. 1, 2020. That means possession remains a crime until Jan. 1, a spokesman for Senate Democrats said.

"In the past 50 years, the war on cannabis has destroyed families, filled prisons with nonviolent offenders, and disproportionately disrupted black and brown communities," Pritzker said. "Each year, law enforcement across the nation has spent billions of dollars to enforce the criminalization of cannabis. ... Yet its consumption remains widespread."

On the campaign trail, Pritzker claimed that, once established, taxation of marijuana could generate $800 million to $1 billion a year in taxes. He initially estimated that in the budget year that begins July 1, dispensary licensing would bring in $170 million. But the lawmakers who sponsored the plan, Sen. Heather Steans and Rep. Kelly Cassidy, both Chicago Democrats, have dampened that prediction, lowering estimates to $58 million in the first year and $500 million annually within five years.

The marketplace portion of the Illinois law also addresses what critics have complained is the decades-long war on drugs' disproportionate impact on minority communities. Pritzker said that while blacks comprise 15 percent of Illinois' population, they count for 60 percent of cannabis-possession arrests.

In addition to providing criminal-record scrubbing for past low-level offenders, the law gives preference to would-be marijuana vendors in areas of high poverty and records of large numbers of convictions. And portions of tax proceeds must be reinvested in impoverished communities.

Police organizations are wary, concerned about enforcing driving under the influence laws and arguing technology for testing marijuana impairment needs more development. Law enforcement organizations were successful in killing an earlier provision that would have allowed anyone to grow up to five marijuana plants at home for personal use. Police said they'd have difficulty enforcing that, so the bill was amended to allow five plants to be maintained only by authorized patients under the state's medical marijuana law. They previously could not grow their own.

Ten other states and the District of Columbia have legalized smoking or eating marijuana for recreational use since 2012, when voters in Colorado and Washington state approved ballot initiatives. Vermont and Michigan last year were the latest states to legalize marijuana. Vermont did so through the Legislature, the first time it wasn't done through a ballot initiative, but didn't establish a statewide marketplace as Illinois did.

Other initiatives have failed. Promising proposals in New York and New Jersey fizzled late this spring. Despite a statewide listening tour on the issue by Pennsylvania's lieutenant governor last winter, the idea never took flight.