Editor's note: Theresa Pierno is acting president of the National Parks Conservation Association, a nonprofit advocacy organization that works to protect the national parks.
(CNN) -- Were you hoping to spend the weekend viewing the beauty of the change of seasons at the Great Smoky Mountains? Are you one of the 24 couples who had a wedding planned on the National Mall in October? Did you plan to visit Half Dome on the 123rd anniversary of Yosemite's establishment in 1890?
Unless something changes soon, you won't be able to do any of those things because of the federal government shutdown. The shutdown has closed the 401 National Park System sites across the country. Visitors will be turned away, gates will be shut, tens of thousands of employees will be furloughed and communities will lose millions of dollars a day.
Only a few hundred yards from the congressional impasse, the National Mall and its Monument Parks in Washington now have a new feature: barricaded landmarks, including the Lincoln, FDR, Jefferson, World War II and MLK Jr. memorials.
National Parks are often called "America's Best Idea," and now they are symbols of political dysfunction. They are not the reason for our country's budget woes. But national parks and the people who rely on them-- visitors, school groups and businesses -- are once again collateral damage in a broken budget process.
What's worse, many national parks have been forced to close during their peak visitation season, places such as Acadia National Park and Rocky Mountain National Park, where people go to enjoy the fall foliage. And many people wait till the cooler months to visit places such as the Grand Canyon and Death Valley.
The potential loss of more than 750,000 daily visitors from around the world -- the number who typically visit national parks in October -- might cost local communities as much as $30 million each day the national parks are closed.
The closure of America's crown jewels threatens the livelihood of park businesses, gateway communities and the American families within them, whose economies rely on national parks being open for business. Families, school groups and tourists from around the world who have made plans to visit and enjoy our national heritage will face disappointment.
Bar Harbor, Maine, adjacent to Acadia National Park, attracts nearly 10,000 visitors daily in October. The loss of these visitors could be shattering to a community that relies on that final flush of tourism dollars before the steep drop-off in winter.
Chris Fogg, executive director of the Bar Harbor Chamber of Commerce, told me that with the impact of the sequester and the late opening of Acadia's roads, business was already down about 30% in April and May in comparison to the average over the last five years. "We just can't believe that Congress is letting this happen," He said. But it is happening. All across the country.
The federal government shutdown has made a bad situation even worse for our national parks. Over the past three years, the National Park Service's budget has been cut by 13%, or about $315 million.
These cuts have already forced national park superintendents to delay the opening of parks or park roads; close visitor centers, picnic areas and campgrounds; decrease the number of rangers to protect and maintain parks; and limit the number of educational programs. Countless students across the country have been denied educational opportunities in national parks and opportunities that would shape their love of the outdoors and parks for the rest of their lives.
We need Congress to do two things: Reopen our national parks and then restore the funding they lost because of the damaging sequester. Our national parks are treasured by Americans nationwide. The federal government has a responsibility to keep them open and adequately funded.
Today, Yosemite's birthday has been spoiled for the American people and for tourists from around the world.
We need Congress and the president to reopen our parks and reach a budget agreement that keeps America's greatest places protected and open from now on.
Follow us on Twitter: @CNNOpinion.
Join us at Facebook/CNNOpinion.
The opinions expressed in this commentary are solely those of Theresa Pierno.