Chicago Mayor Lori Lightfoot is ordering anyone returning from states where coronavirus cases are surging to quarantine for two weeks. The mayor announced the quarantine in a tweet late Thursday afternoon.

This will start at 12:01 a.m. Monday, July 6, after the 4th of July holiday weekend. It impacts visitors to Chicago, as well as current residents who are planning to travel to one of the states where coronavirus cases are on the rise, according to the city.

Notice will be given to travelers via message boards at the city’s two airports, on highways, and through social media. Hotels and rental operators like Airbnb have been asked to communicate the policy to visitors.

Travelers from any of the states flagged by the city are asked to quarantine or face up to $7,000 in fines. According to the city’s website, “a state will be designated if it has a case rate greater than 15 new COVID-19 cases per 100,000 resident population, per day, over a 7-day rolling average.”

Fifteen states have been flagged by the city as of Thursday. They include: Alabama, Arkansas, Arizona, California, Florida, Georgia, Idaho, Louisiana, Mississippi, North Carolina, Nevada, South Carolina, Tennessee, Texas, and Utah.

Chicago plans to update the list every Tuesday starting July 14.

Correction: An earlier version of this story gave the incorrect start date for the quarantine order, which goes into effect July 6.

Claudia Morell covers City Hall for WBEZ. Follow her @ClaudiaMorell.