There were other fueling options, depending on where a railroad operated. In England and in the eastern United States, soft coal (bituminous) was in great abundance. In Montana, mines produced vast quantities of cheap lignite, only slightly more burnable than peat, so Northern Pacific locomotives has huge fireboxes requiring four-wheeled trailing trucks. In some places (Europe, South America), railroads actually used peat as a fuel. And in the coal-less desert Southwest, Southern Pacific and Santa Fe fed medium-grade oil to their locomotives.