Coronavirus updates: State declares public health emergency over case 'surge'

New COVID-19 cases increased nationally over the last week, according to an internal FEMA memo obtained by ABC News.  

In the last seven days, new cases went up 15.1% compared to the previous seven days, the memo said. 

Cases are going up in 22 states and territories, with Colorado in particular seeing a "sharp uptick" in cases last week "primarily related to institutions of higher education," the memo noted. Within Colorado, the counties of Denver, Adams and Boulder had the highest number of new cases over the last three weeks, according to the memo. Boulder County -- home to the University of Colorado-Boulder -- reported the largest number of cases last week, it said.

Wisconsin is also seeing a surge in cases tied to college campuses. Over 80% of all counties in the state have moderate or high levels of community transmission, according to the memo, and a large proportion of the localities with the fastest-growing epidemics have a University of Wisconsin campus. Last week, the University of Wisconsin-Madison reported more than 700 cases, the memo said. Eighteen- to 24-year-olds have a case rate five times higher than any other age group in the state, FEMA found.

Deaths due to COVID-19 were stagnant nationally, according to the memo. In the last week, there was a 0.6% decrease in recorded deaths over the previous week. Virginia had its second-worst week of reported deaths last week, with 238, including the first COVID-19 death in a child in the state, the memo said.

The national test-positivity rate ticked downward slightly in the past seven days, to 4.4%, said the memo. It was 4.6% for the prior seven-day period.

ABC News' Josh Margolin contributed to this report.

In North Carolina, larger outdoor event venues can reopen at 7% capacity on Oct. 2., Gov. Roy Cooper said Tuesday.

The state's positive test percentage has been dropping and is now between 5 and 6%, state officials said.

Meanwhile, North Carolina's Department of Health and Human Services announced a new contact tracing app called "SlowCOVIDNC."

The app will alert people "when they may have been exposed to someone who has tested positive for COVID-19," the Department of Health and Human Services said Tuesday. "It is completely anonymous and does not collect, store or share personal information or location data."

Wisconsin Gov. Tony Evers declared a public health emergency on Tuesday due to a "recent surge in cases among young people."

Eighteen to 24 year olds have a COVID-19 case rate five times higher than any other age group, according to the governor.

"We are seeing an alarming increase in cases across our state, especially on campus," Evers said in a statement. "We need folks to start taking this seriously, and young people especially—please stay home as much as you are able, skip heading to the bars, and wear a mask whenever you go out."

Wisconsin is "experiencing unprecedented, near-exponential growth of the COVID-19 pandemic," the governor's office said.

On Aug. 31, the number of new daily cases reported in the state was at 678. On Monday, the number of daily cases reported was 1,791.

Evers on Tuesday also issued a new face covering order requiring residents ages 5 and older to wear a mask indoors.

The novel coronavirus has now killed 200,000 people in the United States, just eight months after the nation's first confirmed case.

The U.S. death toll from COVID-19 currently stands at 200,005, according to a real-time count kept by Johns Hopkins University.

The first case of the novel coronavirus in the United States was reported in a patient in Washington state on Jan. 20, according to the U.S. Centers for Disease Control and Prevention.

Four months later, on May 27, the U.S. death toll reached 100,000.

The novel coronavirus has now killed nearly twice as many Americans as the 116,516 who died in World War I, the third-deadliest conflict in the nation's history. More than 400,000 Americans died in World War II, while an estimated 655,000 died in the Civil War.

See this additional ABC News coverage marking the grim milestone:

200,000 Americans have died from coronavirus: A look at that grim milestone in context

As US hits 200,000 COVID-19 deaths, experts warn of growing mental health crisis

We've hit 200,000 COVID-19 deaths in 6 months. What will the next 6 months look like?

200,000 American lives lost from COVID-19: Here's what we've learned

WHO on a coronavirus second wave, lockdowns and how the world responded to the pandemic

200,000 dead: Federal response marked by chaotic messaging, unwarranted optimism

ABC News' Marc Nathanson contributed to this report.