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Federal workers in Arizona's national parks and forests and at military installations were furloughed Tuesday with shutdown of non-essential services of the federal government.

By one estimate, as many as 40,000 federal workers in the state could be affected in some way.

Visitor center at Saguaro National Park's West Unit.

Essential services, including federal air traffic control staffing, Border Patrol and other security services, remained in effect. Social Security payments will be made, and the Medicare and Medicaid programs will continue to pay doctors and hospitals.

An estimated 1,600 civilian workers at military facilities at Davis-Monthan Air Force Base in Tucson were being furloughed, a base spokesperson said.

The state's national parks and forests were closed.

Federal funding that supports a variety of programs, including welfare payments for food and cash assistance to families, could end within days, state officials said.

The cuts came after Congress failed to come to terms on a federal budget resolution to continue governmental operations at least temporarily. The hangup is over whether to defund or delay the Affordable Care Act, which Republicans in the U.S. House insist must be part of a budget deal.

Gov. Jan Brewer said in a statement that a federal shutdown "will have an unnecessary and negative impact on services aimed to assist Arizona's vulnerable."

Brewer said her office continues to work with state agencies to ensure that the effects of the shutdown are minimal.