Man spends 3 years on the go, visiting all 419 National Park Service sites

Desert landscapes, war memorials, volcanic craters — if it's a National Park Service site, Mikah Meyer has seen it sometime within the last three years.

On April 29, 2016, Meyer set out to visit all 419 National Park Service sites, not stopping until he reached the final one. He chose that date for a significant reason: It was the 11th anniversary of his father's death. His dad, a Lutheran pastor in Nebraska, was planning on traveling once he retired. Knowing nothing is certain in life, Meyer wanted to celebrate his dad by going on the trip he wasn't able to take.

He visited his final site on Monday: the Lincoln Memorial in Washington, D.C. The last three years were a nonstop adventure, with Meyer driving 75,000 miles in a van and flying to some destinations, like Guam's War in the Pacific National Historic Park. He is an LGBT advocate, and along the way he stopped at about 100 churches, giving sermons and getting to know supporters who made donations to his travel fund.

Meyer, 33, is believed to be the first person to have gone to every National Park Service site in a single trip, and he has inspired others who followed his journey online to go on a similar trek. "I really got to know the American story," he told The Washington Post. "More than just natural wonders, the Park Service sites tell our American story."