On July 27, the CDC updated its guidance to recommend that fully vaccinated and unvaccinated people wear masks indoors in locations with substantial or high coronavirus transmission. According to the CDC, 69.3% of counties in the United States were experiencing what CDC defines as high or substantial levels of transmission as of July 29.

Since the CDC’s announcement, municipal governments with jurisdiction over fourteen of America’s 100 largest cities and Washington, D.C. have announced indoor mask mandates. Four of these cities are located in Nevada, where Gov. Steve Sisolak (D) announced an indoor mask requirement in counties with high or substantial coronavirus transmission, effective July 30. Las Vegas, Henderson, Reno, and North Las Vegas are all located in high transmission counties, according to the CDC, making them subject to Sisolak’s mask order.

In Florida, Mayors Daniella Levine-Cava and Jerry Demings of Miami-Dade County and Orange County, which encompass the cities of Hialeah, Miami, and Orlando, issued indoor mask requirements on July 28. It is unclear whether these requirements will stand, however, due to a state law that allows Gov. Ron DeSantis (R) to preempt local emergency rules.

Four other municipalities issued indoor mask requirements following the CDC’s updated guidance: 

1. In Atlanta, Georgia, Mayor Keisha Lance Bottoms issued an indoor mask requirement on July 28.
2. In Kansas City, Missouri, Mayor Quinton Lucas issued an indoor mask requirement on July 28, effective August 2 through at least August 28. Missouri Attorney General Eric Schmitt announced on July 28 that he planned to file a lawsuit against Lucas challenging the order.
3. In California, Sacramento County Public Health Officer Dr. Olivia Kasirye issued an indoor mask requirement on July 29, effective July 30.
4. Washington, D.C., Mayor Muriel Bowser (D) issued an indoor mask requirement on July 29, effective July 31.

Several municipalities had announced indoor mask requirements prior to the CDC’s updated indoor mask guidance. On July 26, St. Louis County Executive Sam Page, with the support of St. Louis city Mayor Tishaura Jones, issued an indoor mask requirement for the county. On July 28, however, the city council voted 5-2 to invalidate the order. The issue of whether the mandate stands is expected to be decided in court.

In California, Los Angeles County reinstated its mask mandate on July 15, followed by the city of Long Beach on July 16. Honolulu was also subject to indoor mask requirements before the CDC’s updated guidance, due to preexisting statewide guidance in Hawaii.

In total, 39 states issued statewide public mask requirements during the pandemic. At the time of writing, 7 states had statewide mask orders. All 7 states have Democratic governors. Six of the seven states exempted fully vaccinated people from most requirements.

Of the 32 states that have fully ended statewide public mask requirements, 16 have Republican governors, and 16 have Democratic governors. Twenty-nine states ended mask requirements through executive order, two (Kansas and Utah) ended mask requirements through legislative action, and one (Wisconsin) ended its mandate through court order.