Some companies are wading into the fight over the ongoing U.S. government shutdown, offering to help federal workers and soliciting volunteers to provide public services.

Fittingly, outdoor brands took to social media encourage members of the public to look after public land at risk of vandalism and being overwhelmed by garbage. REI urged people to help restore national parks after the shutdown ends, while The North Face suggested donating to the National Park Foundation.

The National Parks Service has been mostly closed since the shutdown started on Dec. 22, leaving millions of acres of government land untended. Hundreds of thousands of government employees are working without pay or are on furlough.

REI CEO: Our national parks need our help. Here’s how you can get involved and volunteer. — REI (@REI) January 12, 2019

Columbia Sportswear CEO Tim Boyle targeted the issue at the center of the shutdown while playing off President Donald Trump's campaign slogan, saying in a tweet: "Make America's parks open again." He added: "Walls shouldn't block access to parks, and federal workers shouldn't be left out in the cold. Work together to open our parks."

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Other companies offered more direct help for federal workers. Restaurant chain Sweetgreen last weekend tweeted an offer of a free salad dinner to anyone showing a government ID, and food conglomerate Kraft opened an outlet in Washington, D.C., stocked with free food for federal workers.

"While we can't do anything about the whole paycheck thing, we'll do what we can to see that family dinners remain business as usual, Kraft announced on Facebook.

Federal workers left unpaid or furloughed collect a free bag of groceries from Kraft Foods on the 27th day of the partial government shutdown in Washington, U.S., January 17, 2019. JOSHUA ROBERTS / REUTERS

USAA, a provider of insurance and other financial services, to military service members, on Wednesday said it would donate $15 million in interest-free loans of up to $1,000 to Coast Guard workers with dependents and $750 to single members.

Some Coast Guard members and their families, as well as TSA personnel, are struggling financially and have had to go to food banks.