strip mining became the most economically feasible method by which to extract coal. Major coal deposits were located near the southeastern Montana settlements of Birney and Decker, and mining soon replaced cattle ranching in the immediate area. The small community of Colstrip grew substantially as it became the site for several major coal-fired power plants associated at the time with Western Energy, a subsidiary of the Montana Power Company. For residents of the region, the characteristic sense of community disappeared. The physical damage to the environment was an important factor as was the influx of miners who then outnumbered the original population. Most damaging, however, was the strife between pro- and anti-development factions in the community. Most of the inhabitants of small towns like Decker, convinced their old lifestyle had been destroyed, moved elsewhere. Residents around Birney, farther from the site of strip mining, remained divided on whether the changes had improved their quality of life. Oil Prospectors discovered numerous small oil fields in the state after 1910. The oil went to small local refineries which marketed the gasoline locally through a network of service stations using the same brand name. After 1945 majors such as Standard Oil of New Jersey (now Exxon-Mobil) and Union Oil of California grew rapidly and by the 1950s owned 80% of refining capacity. In 1949 the value of Montana oil passed the value of copper mining. After 1945 oil production escalated in Alberta, and pipelines were built to Billings to serve the American market. The short-lived Williston Basin boom in the 1950s did not help Montana refiners because pipelines moved the oil out of state for refining. By 1960 Montana refiners depended on Canadian sources. By 2000 only four refineries remained in the state. Production, which peaked at 48 million barrels in 1968, fell by 1990 to less than 20 million, and highly efficient technology significantly reduced employment. After the discovery of oil in the Williston Basin, Glendive became an oil boom town. The small reserves of the basin, coupled with the expense and difficulty of moving the oil out of the area, brought the end of the oil boom in Glendive in 1954. In the 1970s, new discoveries, combined with international fluctuations in the oil industry, created a second boom centered around the community of Sidney. This boom also faded. However new drilling techniques involving horizontal drilling and fracturing technology, made it financially