In 1862, Henry Wilson of Massachusetts mentioned Kephart by name in a speech on the floor of the U.S. Senate as one of the traders who had "polluted the capital of the nation with this brutalizing traffic" of selling people.

[8] Historian Frederic Bancroft introduced Kephart in Slave-Trading in the Old South with the description "Early in the 'thirties a small trader, living near a little ferry on the upper Potomac, was searching for slaves throughout Montgomery and Frederick counties, Maryland.

In 1827 Benjamin Lundy wrote: 'It is my decided opinion that were we to search the globe from Kamchatka to the southern pole, we could not find a people more tyrannical, more completely lost to feelings of humanity and justice, than the heartless wretches who carry on the United States slave trade through Maryland and the District of Columbia.

[15] Between 1837 and 1846 he leased, and between March 12, 1846, and 1859 he owned, the Alexandria, Virginia slave pen originally used by Franklin & Armfield that is now known as the Freedom House Museum, located at 1315 Duke Street.

[20] In 1846 Kephart and Virginia-based trader Joseph Bruin went to chancery court against each other in Fairfax County, Virginia; the case file mentions over 100 different enslaved people.

[27] Kephart sold the building in 1859, it was operated as a slave jail by Price & Cook for a time, and finally it was captured and liberated by the U.S. Army on or around May 24, 1861.

Colored Troops, and who was employed at the Library of Congress from 1876 to 1919,[30] told Frederic Bancroft, "Ever'body in Frederick knowed Kephart, an' was afeerd of 'im, too.

Senator Henry Wilson denounced Kephart as a key slave trader of the District of Columbia in a speech on the floor of the U.S. Senate:[33] In 1830, the Washington Spectator indignantly denounced these "processions so often seen in the streets of Washington, of human beings handcuffed in pairs, or chained in couples," wending their way to the slave ships which were to bear them to the distant South.

"[33]Moncure Daniel Conway's Testimonies Concerning Slavery devoted a chapter called "The Slave Harvest — Mysteries of a Shamble" to George Kephart and his jail.

One elderly man was left behind; per Conway the shackles that bound him were removed and sent to Henry Ward Beecher as a sort of memento of the success of the abolition movement in the United States.

[38] In 1867 George Kephart donated "½ acre of land to the Methodist Episcopal Church of Baltimore County to erect a school house for colored children and a cemetery to bury the dead.

[42][43] The American poet and abolitionist John Greenleaf Whittier visited three slave jails in the District of Columbia in 1841, including the one at 1315 Duke Street.

[44] From this glittering lie my vision Takes a broader, sadder range, Full before me have arisen Other pictures dark and strange; From the parlor to the prison must the scene and witness change Hark!

The heavy gate is swinging On its hinges, harsh and slow; One pale prison lamp is flinging On a fearful group below Such a light as leaves to terror whatsoe'er it does not show.

[46] In 2021, the Kephart Bridge Landing in Loudoun County, Virginia, was nominated for renaming, as the existing name commemorated a major slave trader.