The nonprofit National Parks Conservation Association says the hit this time would be more than twice as large.
Employees would continue to work — without pay — if they are deemed essential to protect life, property and national security. Mandatory spending for Social Security and Medicare benefits would continue. The Affordable Care Act, at the center of the current funding debate in Washington, would also continue to be implemented.
At the Department of Homeland Security, which includes the Secret Service, the Coast Guard, the Transportation Security Administration, Customs and Border Protection and Immigration and Customs Enforcement, most of the 231,117 workforce will remain on the job. Officials said 31,295 would be furloughed.
Agency furlough estimates were nationwide figures, not limited to Maryland.
Members of Congress would continue to be paid.
Across the government, about 1.2 million civilian employees are expected to face furloughs.
NASA spokesman Allard Beutel said a short shutdown probably wouldn't affect the agency's upcoming missions. But he warned an extended closing could cause problems for the Mars-bound MAVEN spacecraft, set to launch from the Kennedy Space Center in Florida in November.
Goddard scientists have been heavily involved in that project.
The repeated budget crises of the past few years also have taken a toll on federal workers' morale. Some cabinet officials Friday urged employees not to take the budget battles personally.
"I know these kinds of actions … don't feel very supportive," Interior Secretary Sally Jewell said in a video message to employees. "I want you to know, and I know the American people know, that the work we do is very, very important."
The Tribune Washington bureau and Baltimore Sun reporters Kevin Rector and Matthew Hay Brown contributed to this article.