Over 2.1 million people were screened at U.S. airport security check points Friday -- the highest checkpoint volume since Aug. 15, Transportation Security Administration spokesperson Lisa Farbstein said.

Americans have flocked to airports to travel for the Labor Day weekend despite the threat of the delta variant and surging COVID-19 cases and hospitalizations.

The U.S.’ daily case average remains around 153,000 cases a day, up by approximately 964% in the last two months.

Overnight Friday, the U.S. recorded its second single-highest day of COVID cases this week with more than 170,000 new cases reported.

Every state in the country is currently experiencing high community transmission. The South still leads the country with the highest case rates. Tennessee, and South Carolina currently have the country's highest case rate, followed by Mississippi, Florida, Georgia and Wyoming, all with case rates above 600 per 100,000 people.

-ABC News' Ahmad Hemingway and Arielle Mitropoulos

This year’s Made In America festival over Labor Day weekend in Philadelphia will go on with COVID-19 restrictions.

Despite surging delta variant cases and flooding from the Schuylkill River that inundated the Ben Franklin Parkway with water, the festival will continue, officials said.

"I think it's good for the city to have this kind of event, so we can celebrate a little bit even in the midst of potential tragedy. Jay-Z, Beyonce, the Biebs (Justin Bieber) is coming," Philadelphia Mayor Jim Kenney said Friday. “It'll be fun for a change...be nice to have some fun, wouldn't it?"

Roc Nation, which is producing the two-day festival, said all attendees will need to wear masks. Attendees will also have to show proof of a negative COVID-19 test or printed proof of full COVID-19 vaccination to get in.

"The negative COVID-19 test result must be obtained within 48 hours of attending the Made In America festival," said Roc Nation on the festival’s website.

Philadelphia officials also updated the city’s mask mandate in August to require masks at all non-seated outdoor events with over 1,000 attendees.

Jacqueline L. Jackson, the wife of civil rights leader Rev. Jesse Jackson Sr, has been released from the hospital after receiving treatment for COVID-19, her family said Friday.

"Our mother is leaving the Northwestern Memorial Hospital and coming home," the family said in a statement. "Our family is grateful to God and the medical team that treated her and that is allowing her body to continue to heal from the COVID-19 virus."

She had been in the ICU after testing positive for the virus. Jacqueline, 77, was not vaccinated.

Her husband Rev. Jesse Jackson, 79, remains at The Shirley Ryan Ability Lab where he’s receiving intensive occupational and physical therapy. He has Parkinson's disease and was vaccinated, ABC Chicago station WLS reported.

"We urge all who have not yet been vaccinated for the COVID-19 virus to do so immediately,” the family said in a statement.

The family had announced the couple was hospitalized with COVID-19 on Aug. 21.

The mayor of Stillwater, Oklahoma, declared a state of emergency for the city that started Friday due to a soaring number of hospital patients and a shortage of medical staff.

Overflow tents have been set up outside the Stillwater Medical Center Emergency Department to deal with the influx.

The state’s department of health is deploying the Medical Reserve Corps. and additional medical professionals to help in overflow tents.

“Our health professionals have incessantly warned us that we may reach the point when much-needed medical attention, COVID or non-COVID related, may not be available,” Mayor Will Joyce said in a release. “We have now reached that critical threshold where our hospital no longer has available staffed beds.”

“It is critical that each of us become fully vaccinated against COVID-19 and wear masks when possible,” he added.

Officials said Stillwater Medical, which serves in a six-county area, is at full capacity.

In the crisis, residents and visitors who go to the hospital for treatment over the weekend may be diverted to nearby or out-of-state facilities.

There are zero ICU beds available across the four largest hospital systems in Oklahoma City, ABC local affiliate in Oklahoma City KOCO reported.

Concerns are mounting especially as Stillwater hosts events and activities that kick off Saturday and have the potential to attract an influx of 40,000 visitors.

Dr. Paul Offit, a member of the U.S. Food and Drug Administration's vaccine advisory committee, said a two-dose COVID-19 vaccine "appears to be enough" to curb infection, rather than adding a booster shot.

"You look at states in the United States that have high immunization rates with a two-dose vaccine, it appears the two doses appears to be enough to be able to control this infection," Offit, who is also the director of the Vaccine Education Center at Children's Hospital of Philadelphia, told ABC News on Thursday night. "I think the critical issue here is not going to be boosting the vaccinated. I think if we really want to get on top of this pandemic, it's going to be about vaccinating the unvaccinated."

The FDA's vaccine advisory committee is set to hold a key meeting on COVID-19 vaccine booster shots on Sept. 17, just three days before the Biden administration plans to begin offering the shots to Americans.

"If the companies or the FDA can make a case that there has been an erosion in protection against severe critical disease and that that erosion in protection against severe disease would be mediated or eliminated by a third dose, then we could move forward," Offit said. "But to date, we really need to see those data to be able to make that decision."