The discovery of high-quality slate in the area led to Ijamsville's brief era as a mining town, which lasted until it transitioned 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.

In 1785, a Maryland native named Plummer Ijams moved to Frederick County, having purchased a tract of land called the "Paradise Grant" from the government.

[3] The land was approximately 8 miles (13 km) southeast of the city of Frederick and cost Plummer one pound, fifteen shillings, and four pence per acre.

[4][5] Plummer established a plantation on his new land, growing primarily wheat and barley, with a small number of slaves.

Plummer Jr. built a gristmill along nearby Bush Creek (which stood until demolished in 1994) while John enlisted in the War of 1812 and rose to the rank of captain.

The Duvalls discovered large deposits of slate in 1800, and two quarries were operational by 1812, at least one owned by a man named Gideon Bantz.

[10] In fact, Ijamsville slate was used as roofing material throughout Frederick and even in Washington, D.C.[11] Many small shops grew up towards the center of the town, catering to the needs of residents.

By that time, the town could boast a coppershop, carpenter's shop, wheelwright, stable, boardinghouse, shoemaker, milliner, and the gristmill and a sawmill constructed by the original Ijams residents (sold in 1874 to the McComas family for around $6,900).

Local Episcopalians donated a land lot to the cause, farmer Charles Hendry fired the bricks, and the women of the town made and sold quilts to raise the needed funds.

Unfortunately for the town, when Wolf journeyed to Vermont in 1876, hoping to form a full-fledged company and return, he caught pneumonia and died.

Though Lady Ellen and some of the couple's students often claimed that she was the book's true author and requested that her relative, R. D. Blackmore, publish it under his name, no definitive proof was ever given for their story.

One of the town's only crimes—the midnight robbery of the Turner family mill by three "highwaymen"—occurred during that summer, but Ijamsville otherwise remained a "quiet country village".

From that time on, Ijamsville residents were serviced by local Frederick County schools (in particular those of nearby Urbana, Maryland).

A large patch of grass sandwiched between a hill and the railroad tracks known as Moxley Field housed the Ijamsville champion baseball team.

[22] The hospital was initially open to both men and women, but the lack of male nurses during World War I forced the owners to limit it to only female patients.

An advertisement from the era claimed "each patient received individual psychotherapeutic attention, occupation, and recreation... under the most favorable hygienic conditions".

As the older farm owners died and their children moved closer to city centers, more and more land was put up for sale.

Houses were built and filled with families looking for work in nearby Frederick, Baltimore, or Washington, D.C.[25] By 2000, Ijamsville was divided into three areas: the original town center by the railroad tracks, with a few historic homes, left intact; several large family farms raising mostly cows, corn, and soybeans; and large sections of suburban-style homes.

[27][28] Two religious centers were established as well: a Roman Catholic, Jesuit Saint Ignatius of Loyola parish (originally from Buckeystown, MD and with another church building in Urbana); and the Hindu Sri Bhaktha Anjaneya Temple, the "only [Hindu] temple in the United States dedicated to [Bhaktha]-Anjaneya.

[35] The Christian Life Center, a United Pentecostal organization from Rockville, MD, purchased land near FMS in early 2012 and began holding services in Damascus High School.