Illinois Gov. JB Pritzker announced Wednesday that all pre-K through 12th grade schools and day cares must follow universal masking indoors regardless of vaccination status.

Pritzker said the state is facing a growing threat from the delta variant and noted that children under 12 aren't yet eligible for COVID-19 vaccines.

"Far too few school districts have chosen to follow the federal Centers for Disease Control and Prevention prescription for keeping students and staff safe," he said at a news conference. "Given the CDC’s strong recommendation, I had hoped that a state mask requirement in schools wouldn’t be necessary, but it is."

The latest delta surge is once again pushing hospital staffing to breaking points across the U.S.

In Alaska, Idaho, Oregon and Washington, some "facilities are experiencing substantial shortages of both clinical and support staff," according to a Department of Health and Human Services planning document obtained by ABC News Wednesday.

In hard-hit Missouri, many hospitals "don’t have the staff to support a surge without further modification to operational strategies," the document said.

At a Shreveport, Louisiana, hospital, where the number of COVID-19 patients are multiplying, nurse Melinda Hunt told ABC News, "To be honest, I probably cry most days at work. And I cry at home. I’m tired. I’ve been doing this a year and half. It feels like it’s never going to end."

The U.S. daily case average has climbed to more than 84,000, a 45.3% jump in the last week, according to federal data.

The daily case average is now more than seven times higher than it was six weeks ago.

All but three states are now reporting high (a seven-day new case rate ≥100) or substantial (a seven-day new case rate between 50-99.99) community transmission, according to federal data.

-ABC News’ Arielle Mitropoulos

The delta variant now accounts for 93% of all sequenced cases in the U.S., according to the latest CDC data, which was collected over the last two weeks of July.

Delta accounted for just 3% of cases sequenced in late May.

Across the Midwest, described as HHS regions 7 and 8, delta made up 97% to 98% of cases. This includes Iowa, Kansas, Missouri, Nebraska, Colorado, Montana, North Dakota, South Dakota, Utah and Wyoming.

-ABC News’ Cheyenne Haslett

Hundreds of student and staff members from the Marion School District in Arkansas are now quarantined in only the second week of the school year, officials announced.

The state has a ban on school districts imposing a mask mandate.

On Tuesday, the district said 253 students would begin their two-week quarantine due to 15 cases that were reported in the schools. This came after 168 students were already quarantined last week.

"If all students and teachers had been wearing a mask appropriately- then today's 15 positive cases would be isolated- but there would be no resulting quarantines for anyone else," the district said in a statement.

Arkansas Gov. Asa Hutchinson told reporters Tuesday he regretted signing the bill that banned masks in schools and urged the state legislature to amend the law to give schools the option.