For the 18th time in American history, the U.S. federal government encountered a shutdown on Tuesday.

Prior to each new fiscal year, the House of Representatives, the Senate and the President must unite to appropriate and prioritize federal funding to government-owned agencies as well as set spending limits.

Passed by Congress and signed by the President, the budget requires majority agreement on proposed government spending in the coming year. Alternatively, a "continuing resolution" may be passed, which maintains the same operational spending limits as the previous year.

But neither happened. The primarily-Democratic Senate and the heavily-Republican House of Representatives could not agree on the terms of a continuing resolution. The House added an initiative to the resolution that would prevent the Affordable Care Act from taking effect for another year and repealed a tax on medical devices. The Senate could not condone this delay.

Eventually, time ran out.

As it became increasingly clear that no such compromises would be reached, the Office of Management and Budget asked federal agencies to form contingency plans in the event of a shutdown, splitting staff into "essential" and "non-essential" employees.

Both groups do not receive pay during the shutdown period, but essential employees must continue to work.

Without a continuing resolution or a finalized budget, many departments of the federal government cannot receive the money they need to function and must close down until a budget emerges. The Affordable Care Act, however, draws from mandatory spending, meaning it takes effect this month despite the shutdown.

Kenneth Baker, a senior lecturer in the department of economics, said that vital civil services have ground to a halt.

"The National Institute of Health stops research on new drugs," Baker said, "the Center for Disease Control and Prevention stops their flu program, the Department of Housing and Urban Development will cut down on housing assistance ... the Commodity Future Trading Commission, which oversees trillions of dollars of futures derivatives trading will shut down, the Department of Agriculture will cut off its support for the Women, Infants and Children program that helps some nine million low income pregnant mothers buy food, and so on and so on."

Some programs will continue to function: American embassies, air traffic control, emergency medical care, border patrol, federal prisons, law enforcement, emergency and disaster assistance. Others, such as immigration, parks and museums and regulatory agencies, will not.

Independently funded institutions, like the U.S. Postal Service and the Federal Reserve, will not be affected.

Steven Thai, an employee in the Office of Public Affairs for the U.S. Department of Energy, stated that due to the shutdown, facilities like Y-12 will suffer in the meantime.

"This lapse in appropriations has serious impacts on the Department's ability to carry out its mission," Thai said. "The Department will be able to operate for a short period of time after Sept. 30. However, if a resolution is not achieved in the near term, the Department will be forced to take further action to shutdown nonessential operations, resulting in employee and contractor furloughs."

Terry Maddox, executive director of the Great Smoky Mountains Association, emphasized the far-reaching effects of the shut down.

As the park's oldest non-profit partner, Maddox said he expects financial ruin.

"The month of October makes our budget work for the entire year," Maddox said. "Today we will lose $40,000 in sales because the visitors centers are closed."

Maddox expects surrounding communities will also sustain damage.

"It's a blow for the region because our whole economy in the region is based around the national park, so it's going to hurt all the businesses in our region," he said. "And most of those are not government employees. Those are people who are making a living off of being fortunate enough to be close to a national park."

According to the Washington Post, there are currently 1.3 million "essential" federal workers and 1.4 million active-duty military members still working during this period of stagnation. For these employees, retroactive compensation is possible, but not certain, meaning Congress may or may not choose to pay them once business resumes.

John Scheb, Ph.D. and head of the UT political science department, anticipates more than brief financial strain.

"I think it also negatively affects the general perception of Congress and of politicians," Scheb said. "Ultimately, the shutdown feeds cynicism and further corrodes confidence and trust in government."

The shutdown may capture headlines now, but Baker said he sees a much greater problem looming ahead.

"The U.S. is set to run out of money to pay interest on its past bills on the 17th of this month," Baker said. "Most every economist agrees if we default on our payments, it could lead to potentially significant negative economic consequences."