“Make America’s Parks Open Again,” Columbia Sportswear Company’s Tim Boyle  pleaded in a full page ad that ran Friday in The Washington Post.

The statement refers to the U.S. national parks sites that remain closed during the partial government shutdown.

According to the National Parks Conservation Association, about a third of U.S. national park sites are completely closed.

Gates at other sites remain open, but most staff are furloughed for as long as the shutdown continues.

In his statement, Boyle said, “Walls shouldn’t block access to parks, and federal workers shouldn’t be left out in the cold. Work together to open our parks.”