He was a close friend of future President Abraham Lincoln from his days in Springfield, Illinois, where Speed was a partner in a general store.

On April 15, 1837, Lincoln arrived at Springfield, the new state capital, to seek his fortune as a young lawyer, whereupon he met Joshua Speed.

Lincoln sublet Joshua's apartment above Speed's store, becoming his roommate, sharing a bed with him for four years, and becoming his lifelong best friend.

[13] Although bed-sharing between same sexes was a reasonably common practice in this period, this has led to speculation, including by Professor Thomas Balcerski, regarding Lincoln's sexuality.

Joshua announced plans to sell his store and return to his parents' large plantation house, Farmington, near Louisville, Kentucky.

Lincoln, though notoriously awkward and shy around women, was then engaged to Mary Todd, a vivacious society young woman also from Kentucky.

During his stay at Farmington, Lincoln rode into Louisville almost daily to discuss legal matters of the day with Attorney James Speed, Joshua's older brother.

I confess I hate to see the poor creatures hunted down, and caught, and carried back to their stripes, and unrewarded toils; but I bite my lip and keep quiet.

You ought rather to appreciate how much the great body of the Northern people do crucify their feelings ...[16]During Lincoln's presidential administration (March 4, 1861 – April 15, 1865), he offered Speed several government appointments.

Speed disagreed with Lincoln on the slavery question but remained loyal, and coordinated Union activities in Kentucky during the American Civil War.

His brother, James Speed, served as Lincoln's United States Attorney General, beginning in November 1864.

[17] After the assassination of Lincoln by John Wilkes Booth, Speed organized a memorial service in Louisville for the departed leader.

[19] In 1999, the author and gay activist Larry Kramer claimed that he had uncovered new primary sources which shed fresh light on Lincoln's sexuality.

The items were supposedly discovered hidden beneath the floorboards of the old store in which the two men lived, and they were said to reside in a private collection in Davenport, Iowa.

[20] Kramer died in 2020 and apparently never produced or showed anyone the supposed documents[21] although he published a novel in 2015, including some of his ideas about Speed and Lincoln that historian and psychoanalyst, Charles Strozier, found unconvincing as a matter of history or sexuality.