Ijamsville is an unincorporated community located 7 miles southeast of Frederick, in Frederick County, Maryland, United States. The town was founded by Plummer Ijams, a descendant of Welsh immigrants, from whom the town took its name. The discovery of high-quality slate in the area led to Ijamsville's brief era as a mining town, which lasted until its transition to agriculture in the mid-1800s. In the mid-to-late 20th century, large quantities of land in Ijamsville were purchased by developers, and the town became primarily residential as a suburb of Frederick, Baltimore, and D.C..