The workweek kicked off Monday with the federal government still in shutdown mode.

Critical government functions continued, but other agencies and employees were on furlough by Monday as lawmakers continue to fight over any spending package to re-open the government.

As the federal government remains shuttered, here’s a look at what’s open and closed.

What is open and working?

Military

The U.S. military will continue its operations overseas – although members will not receive pay until Congress approves funding.

Defense Secretary Jim Mattis said a shutdown will still have far-reaching effects on the Defense Department.

Weapons and equipment maintenance will shut down, military intelligence operations would stop and training for most of the reserve force would be put on hold, he said. And any National Guard forces heading out to do weekend training duty around the country would be told to go home.

Rep. Tom MacArthur, R-N.J., co-sponsored legislation that would ensure service members receive a paycheck during the shutdown instead of lawmakers.

Airlines

Air travel will remain open during the shutdown as air-traffic controllers are considered essential workers, according to USA Today.

Nearly 53,000 of 58,000 TSA workers will continue to be paid during the shutdown, USA Today reported. And the more than 25,000 air-traffic control employees with the Federal Aviation Administration will also receive their paychecks.

Statue of Liberty

The State of Liberty and Ellis Island were originally closed to visitors over the weekend, but it re-opened Monday with funding from New York’s tourism budget, Gov. Andrew Cuomo said.

“New York will always stand up for the core values that make our nation truly great,” Cuomo said in a statement. “New York State will not allow the vitriol of Washington to close the Statue of Liberty.”

The Democratic governor said it costs $65,000 per day to keep Ellis Island and the State of Liberty National Monument open.

Federal Courts

The federal judiciary will remain open at least until Feb. 9, the U.S. Courts said on its website. It will use court fee balances as well as additional funds that are “not dependent on a new appropriation” to stay open.

“Most proceedings and deadlines will occur as scheduled,” it said.

“If the shutdown were to continue past three weeks, and exhaust the Judiciary’s resources, the Judiciary would then operate under the terms of the Anti-Deficiency Act, which allows work to continue during a lapse in appropriations if it is necessary to support the exercise of Article III judicial powers. Under this scenario, each court and federal defender’s office would determine the staffing resources necessary to support such work.”

Some national parks

Some national parks are open – and some are closed.

The USS Constitution, the world’s oldest commissioned warship, was to remain open to tourists during the shutdown at the Charleston Navy Yard in Boston.

The Smithsonian museums and National Zoo also opened on Monday.

But Big Cypress National Preserve, Everglades National Park and other federally managed natural areas in Florida were partially closed.

U.S. Post Office

You’ve got mail! The U.S. Postal Service will remain open during the shutdown because it is “an independent entity that is funded through the sale of our products [and] services, [and] not by tax dollars,” it said in a tweet.

Social Security

The Social Security Administration will remain open through the shutdown because of its 2018 contingency plan.

What is closed or impacted?

Centers for Disease Control and Prevention

As the nation still grapples with the flu epidemic, nearly 2/3 of the Centers for Disease Control and Prevention staff is furloughed, WAGA-TV reported.

Although the CDC’s contingency plan allows it to “continue minimal support to protect the health and well-being of U.S. citizens here and abroad,” the shutdown will result in “significantly reduced capacity to respond to outbreak investigations, processing laboratory samples and maintaining the agency’s 24/7 emergency operations center,” according to WAGA.

Air Force athletics

The Air Force Academy canceled all athletic events as the government remains shuttered.

“Due to the government shutdown, all Air Force Academy home and away intercollegiate athletic events have been canceled until further notice. In the event a solution is reached, the Academy will work to reschedule as many missed events as possible,” the Academy said in a statement.

Some national historic sites

Martin Luther King Jr.'s childhood home, historic Ebenezer Baptist Church and the visitor center at MLK National Historic Site in Atlanta were closed.

The Liberty Bell and Independence Hall are closed as well.

Library of Congress

The Library of Congress is closed and shut the book on all public events during the government shutdown, it said in a statement.

The Associated Press contributed to this report.