DENVER (AP) — When the government shut down in 2018, a Mississippi nonprofit interceded to fund a bare-bones crew to keep one of the state’s most-visited cultural attractions operating. Now, the group is committed to doing that for Vicksburg National Military Park once again.

The hilly Civil War battlefield where soldiers fought for control of the Mississippi River in 1863, run by the National Park Service, reopened Thursday thanks to a commitment from the Friends of Vicksburg National Military Park and Campaign to pay $2,000 a day to keep it open during the current shutdown.

“For us it is primarily and first and foremost an issue of protection of the park,” executive director Bess Averett said of the site, home to more than 18,000 graves of veterans from six wars and a few former park employees. “During shutdowns or times when the park is not staffed, it’s really vulnerable to vandalism and relic hunters.”

The Park Service’s contingency plan allows parks to enter into agreements with states, Native American tribes, local governments or other groups willing to donate to keep the sites open.

Organizations that support individual national parks across the country have also stepped forward to welcome visitors. West Virginia Gov. Patrick Morrisey also signed a donation agreement to reopen the visitors’ centers at the state’s two national parks.

Many national parks have remained largely open but with visitors’ centers closed. The U.S. Interior Department has released only limited information and directed people to the general contingency plan for how its more than 400 sites should operate under reduced staffing during the shutdown.

The plan allows parks with certain recreation fees to use that revenue to provide basic services like restrooms, trash collection and law enforcement. Hayley Smith and her two children, who were traveling from Louisiana to Arkansas, were among those who visit the park this week despite limited access.

National parks play a critical role in preserving the heritage and environment of America, and raising funds to keep them open during shutdowns ensures their preservation even in difficult times. With various groups coming together, the hope remains that visitors can continue to enjoy these national treasures.