The original vegetation of Minnesota consisted of deciduous and coniferous forests. Early European exploration and logging followed the waterways, which were the primary means of travel. The large pine forests located between the Mississippi and St. Croix Rivers were heavily logged within 30 years in a non-sustainable manner. This led to catastrophic fires in 1871, 1894, and 1918 that destroyed millions of acres and killed thousands due to poor logging practices and a lack of seed sources to regenerate the forests. After the fires, sustainable forest management practices were implemented, including setting land aside and requiring forest management plans.