When the national parks were set up in the 2nd half of the 1800s they faced strong opposition—many policy makers couldn’t understand how undeveloped areas would make money. Fast-forward to our times and the US National Park system is as lucrative as any business model. In 2013 alone the National Parks generated $26.5 billion in economic activity, and visitors spent $14.6 billion on trips to national parks, all the while supporting jobs that employed 240,000 people.