Erie grew from the discovery of coal in the mid-1800s. Its mines became the largest suppliers of lignite coal in the northern Colorado coalfield. Unions quickly moved into Colorado to push for improved working conditions and miners' rights to participate in decisions affecting their jobs. When mine owners refused to honor their requests, miners went on strike, and owners hired scab labor from Europe, Asia, and Mexico. Tensions mounted, and local miners sabotaged mines by setting explosives and otherwise damaging property. Colorado's governor established a special militia to deal with the strikers. The armed militia wounded and killed miners and their families in southern Colorado's Ludlow Mine and Erie's Columbine Mine. Government intervention and the sympathetic viewpoint of the owner of the Columbine Mine led to the first Colorado coal company to unionize. Miners fought for working conditions that characterize many of today's best-run companies. With the closing of the last mine in the area in 1979, Erie has grown to become a bedroom community in the Denver-Boulder metropolitan community.