Many national parks have historic lookouts that are (or should be) listed on the National Historic Lookouts Register. Visitors who know where to look can see lots of splendid examples. By the early 1900s, the early detection and prompt suppression of forest fires had become an important responsibility of state and federal natural resource management agencies. With huge tracts of forested land to look after, the National Park Service became heavily invested in this effort soon after the agency was created in 1916. As more and more national parks were established , many of them carved out of forested lands with long-established fire suppression programs, the Park Service gained a healthy share of the roughly 9,000 lookouts and observation stations ensconced on federal lands throughout the country by 1930. The Civilian Conservation Corps constructed hundreds of new ones and replacements during the 1930s.
http://www.nationalparkstraveler.com/2009/10/when-visiting-national-parks-look-historic-lookouts4713