A century ago, the government hired unemployed young men to build America's forests, trails, and parks. Photos show FDR's 'tree army.'

Source: Business Insider

The Civilian Conservation Corps planting seedlings. Universal History Archive/Universal Images Group via Getty ImagesThe Civilian Conservation Corps was part of Franklin Roosevelt's New Deal. Enrollees became known as the "tree army" because of how many they planted, over 2 billion.