Many forces behind alarming rise in virus cases in 21 states

NEW YORK (AP) — States are rolling back lockdowns, but the coronavirus isn't done with the U.S.

Cases are rising in nearly half the states, according to an Associated Press analysis, a worrying trend that could worsen as people return to work and venture out during the summer.

In Arizona, hospitals have been told to prepare for the worst. Texas has more hospitalized COVID-19 patients than at any time before. And the governor of North Carolina said recent jumps caused him to rethink plans to reopen schools or businesses.

There is no single reason to explain all the surges. In some cases, more testing has revealed more cases. In others, local outbreaks are big enough to push statewide tallies higher. But experts think at least some are due to lifting stay-at-home orders, school and business closures, and other restrictions put in place during the spring to stem the virus's spread.

The virus is also gradually fanning out.

“It is a disaster that spreads,” said Dr. Jay Butler, who oversees coronavirus response work at the U.S. Centers for Disease Control and Prevention. “It’s not like there’s an entire continental seismic shift and everyone feels the shaking all at once.”

The virus first landed on the U.S. coasts, carried by international travelers infected abroad. For months, the epicenter was in northeastern states. More recently, the biggest increases have been in the South and the West.

The AP analyzed data compiled by The COVID Tracking Project, a volunteer organization that collects coronavirus testing data in the United States. The analysis found that in 21 states as of Monday, the rolling seven-day average of new cases per capita was higher than the average seven days earlier.

Here's what's driving increases in some of the states with notable...