A second wave of cities, including Boston, Detroit, New Orleans and Philadelphia, are seeing increases in confirmed coronavirus cases, and could become epicenters for the outbreak if they’re not able to bring those cases under control soon.

Why it matters: Whether these cities can prevent their outbreaks from spiraling out of control will be a major test for the U.S.’ ability to contain the virus.

New Orleans in particular is nearing a crisis, with hospitals already becoming overwhelmed and supplies of medical safety gear running low, per the NYT.