As if you really needed another excuse to get out and enjoy the great outdoors, tomorrow is National Public Lands Day, which means it’s also fee-free day at many federal public lands, including national parks!

National Public Lands Day is expected to bring 170,000 volunteers to more than 2,000 sites across the U.S., in the largest single-day volunteer effort for public lands in the United States. Volunteers will be helping to preserve and protect our “great legacy”, as Department of the Interior Secretary Ken Salazar notes:

Volunteers at last year’s event:

• Collected an estimated 23,000 pounds of invasive plants
• Built and maintained an estimated 1,500 miles of trails
• Planted an estimated 100,000 trees, shrubs and other native plants
• Removed an estimated 500 tons of trash from trails and other places
• Contributed an estimated $17 million through volunteer services to improve public lands across the country

On that same day, the Bureau of Land Mangement (BLM) is hosting a social media meetup, so if you’re out volunteering, you can share stories and photos with the BLM by tweeting to @BLMNational or @publiclandsday and by using the hashtag #NPLD on both Twitter and Instagram.

Find out more: National Public Lands Day