If you thought shutting down the U.S. government was tough, just wait until agencies try to open again for business.

The legislation passed by Congress last night to raise the debt ceiling and fund the government into 2014 will bring hundreds of thousands of federal workers back to their jobs and reopen national parks and museums. Yet it may be weeks or even months before the government resumes issuing loans, payments and contracts at a normal pace.

“This has been very disruptive,” Larry Allen, president of Allen Federal Business Partners, a contract consulting firm in McLean, Virginia, said in an interview. “The shock wave will last for months.”

The partial halt in government operations was shorter than the budget shutdowns in 1995 and 1996 that lasted a total of 26 days. This year’s disruption has been far broader in scope, said Barry Anderson, who was assistant director of the White House Office of Management and Budget during the fiscal 1996 shutdown.

Congress had completed seven of its 13 annual appropriations bills funding agencies in the previous stoppage - - leaving vast parts of the government still working. This time not a single agency funded at Congress’s discretion had final budget approval.

“Things are very different now,” Anderson said.

Federal agencies were instructed to begin opening offices today in a “prompt and orderly manner,” according to a memo from OMB Director Sylvia Burwell that cleared furloughed employees to return to work.

Bill Signed

“We will work closely with departments and agencies to make the transition back to full operating status as smooth as possible,” Burwell said in the memo released early today after President Barack Obama signed the bill ending the shutdown.

The 16-day halt in operations at many federal agencies shaved at least 0.6 percent from fourth-quarter 2013 gross domestic product growth, or taken $24 billion out of the U.S. economy, Standard & Poor’s said yesterday.