The Joppa ZIP code (21085) extends 6 miles (10 km) north of Joppatowne, as far as Benson, just south of Bel Air.

This first attempt to establish an English settlement on the Gunpowder River was apparently abandoned because it proved to be a poor location.

Though documents and records exist for the settlement, including official papers in the archives of the United Kingdom, nobody knows exactly where it was located.

Its location cannot be accurately pinpointed because at that time the mouths of the Big and Little Gunpowder were about a mile further inland (above present-day U.S. Route 40).

St. John's Parish of the established Anglican Church temporarily moved inland, to where the Officer's Club at the Edgewood area of Aberdeen Proving Ground is currently located.

After the decline of Joppa following the designation of the city of Baltimore as the county seat in 1768, St. John's Parish was moved to nearby Kingsville in the late 18th century, where it has stayed.

[5] ... the Assembly directed the site at Foster's Neck "to be deserted, and in lieu thereof fifty acres to be erected into a town on a tract of land on the same river, belonging to Anne Felks, and called Taylor's Choice, and the court-house to be built there."

Joppa was Maryland's most important commercial center in colonial times, with tobacco being the primary commodity crop and export.

The original post road to Philadelphia also went through Joppa,[9] and a ferry across the Gunpowder River connected to points south via what is now the community of Chase and Eastern Avenue.

Economic growth was also stimulated via the establishment of various commercial enterprises just north of Joppa, which used water power generated by Little Gunpowder Falls.

By the end of the 18th century, agricultural and other land development upstream caused the Gunpowder River and Joppa's harbor to silt up, making access by large ships impossible.

In 1961 the Panitz Brothers Company acquired the land from Beulah Hare Chell to develop a planned community Joppatowne.

Maryland Historical Society records show the property was owned by the "Maryland-Virginia Joint Stock Land Bank" in 1936, during the heart of the Great Depression.

On July 11, 1864, Confederate cavalry under the command of Colonel Harry W. Gilmor attacked the Philadelphia, Wilmington and Baltimore Railroad (now Amtrak) train bridge over the Gunpowder River, next to Foster Branch, at what is now the southeastern border of Joppatowne.

Its warehouses have rotted away, its wharves have disappeared, its harbor has become filled with alluvial deposits, its streets have been turned into ploughed fields.

Upon its very site have camped the Indians and in the ruins of the silent town they may have kindled their campfires from the rotten timber of its fallen houses.

After the removal of the county records to Baltimore, which was attended with considerable turbulence, the old court-house at Joppa was sold, and soon crumbled away; the town wharves, at which hundreds of the largest merchantmen had laden, were gradually deserted for those of her more prosperous rival; and her dwellings disappeared one by one, until at the present day their foundations can scarcely be traced, and a solitary tenement of antique style and venerable appearance on the Harford shore of the Gunpowder River, about a mile northwest of the railroad bridge, alone marks the spot where Joppa once stood.The area where the town at Joppa[9] formerly stood was used as farmland (mostly string beans) until 1961.

The original townsite at Joppa,[9] including the Rumsey Mansion, was slated to be developed as Joppatowne's "swim and tennis club".

People interested in historical preservation opposed this plan, but were nearly ignored until the matter reached the attention of First Lady Jacqueline Kennedy.

The Panitz Company sold and donated additional adjacent lots to the Episcopal Church, effectively preserving about 50% of the land where the town at Joppa[9] had stood (the northern half of the site had already been considerably developed).

[9] The Church of the Resurrection has preserved the archaeological ruins and served as a repository for documents, research, and artifacts related to the colonial town at Joppa.

As of 2012, Case Mason in Joppa manufactures and fills products for the Rosebud Perfume Company in Woodsboro, using tins made in Baltimore.

Newt Gingrich, former Speaker of the United States House of Representatives; William R. Forstchen, and Albert S. Hanser wrote an alternate history novel called Grant Comes East: A Novel of the Civil War.