Illinois Governor JB Pritzker announced the measure on Friday.
New York, Illinois and Calfiornia – which include the three largest cities in the US, respectively New York City, Chicago and Los Angeles have all ordered their residents to stay home unless they have essential reasons to go out.
Pritzker explained during a news conference on Friday that experts recommended an urgent, statewide stay-at-home order in order to save lives.
“Left unchecked, cases in Illinois will rise rapidly,” the governor warned.
The order will take effect on 5pm this Saturday 21 March and is currently set to end on 7 April.
Residents of the state will still be able to go outside to visit grocery stores, pharmacies, medical offices, hospitals and gas stations.
They will be permitted to go for runs, hikes, and to walk their dogs.
“For the vast majority of you already taking precautions, your lives will not change very much,” Pritzker said.
He warned against panic buying and stockpiling, adding: “There is absolutely no need to rush out to a grocery store or gas station. On Sunday, and Monday, and Tuesday, and every day thereafter, those will be available to you.”
“Agriculture and the press, veterinarians and plumbers, laundromats and banks, roads, bridges and transit – the fundamental building blocks that keep our society safe and steady will not be closing down,” he said.
“You can still pick up dinner from your local restaurant, pick up your prescriptions, and just spend time with your family.”
Non-essential businesses must stop operating. Those who can work from home must do so.
Essential workers will be provided with safe daycare options, Pritzker said.
His office is ordering municipalities across the state to stop all evictions. School districts will keep providing meals.
Pritzker said he was unable to say when schools would safely reopen. The tentative reopening date has been postponed to 8 April.
“To be honest, we don’t have the resources, the capacity, or the desire to police every individual’s behaviour,” he said, adding he would be “relying on Illinoians to be good members of their communities and good citizens, working together to keep each other safe.”
Law enforcement has been instructed to monitor the situation and “take action when necessary”.
“The easy thing to say today is that soon, everything will go back to the way it was,” Pritzker said. “But I want to be honest with you about that too: we don’t know yet all the steps we’re going to have to take to get this virus under control.”