Benjamin Banneker

Free black men were scarce in Maryland in 1790. Fewer still received any education. Only one was a genius. His work not only helped a new nation stake out a capital city, but his intellect challenged Thomas Jefferson’s racism. His name was Benjamin Banneker.

Postage stamp honoring Benjamin Banneker was issued in 1980.

Postage stamp honoring Benjamin Banneker was issued in 1980.

    Interracial children dotted the Southern landscape as white planters mated with slave women. Banneker was an exception. His white grandmother, Mary Welsh, had come to America as a convicted thief indentured to a planter. Known as Molly, she later rented and farmed land and owned two slaves, both of whom she later freed.  One, a reputed African chief named Bannaka or Banna Ka, became her husband. Their daughter also married a freed slave.

Freedmen made up less than five percent of the black population of Baltimore County, where Benjamin was born Nov. 9, 1731 on the family’s 100-acre farm. A world in which he might be kidnapped and sold into slavery kept Banneker close to home most of his life, growing up with three sisters.

Grandmother Molly taught him to read, using the Bible as their text, and a briefly attended a

Quaker school, where he showed aptitude in mathematics and mechanics. The farm took most of his time, however, where the family grew tobacco and vegetables. He applied his mechanical knowledge to irrigation systems and used crop rotation to help the farm thrive.

Banneker was something of an entomologist, too. He was the first to track the 17-year locust cycle. In his later years he studied bees.

In 1772 a Quaker family moved to the area, and Banneker befriended the Ellicott brothers – Andrew, John and Joseph – who built a gristmill on their property. Andrew’s son George, a mathematician, loaned Banneker books and instruments to study higher mathematics and astronomy. Using them, Banneker predicted a 1789 solar eclipse. He was the first to say that Sirius was composed of two stars, not one – a conclusion not confirmed until the Hubble Telescope two centuries later. He was among the few to suggest that sentient beings lived on other planets.

    After the Revolution, the new United States government set up in New York before moving to Philadelphia. But in 1790 Congress faced the critical question of whether the federal government should establish a national bank in Philadelphia to assume the war-time debts of the states. In order to get Southern states to approve such an action, Congress agreed to locate a permanent capital in the heart of slave territory at Alexandria, Virginia, one of the four busiest seaports in the country.    

    On Jan. 24, 1791 GW announced that the 10- by 10-mile square tract would straddle the Potomac River between Maryland and Virginia. (The Virginia portion was retroceded to that state in 1846.) Andrew Ellicott was the geographer general of the United States. His line of 31 degrees N latitude still defines the boundary between Alabama and Florida. He also tutored Meriwether Lewis on survey techniques and later taught mathematics at West Point. Ellicott chose his friend Banneker to help him survey the District of Columbia and lay out the new city. Boundary stones were placed every mile of the 40-mile perimeter, and Banneker’s calculations played a critical role in establishing key points in the city.

Map from 1906 shows the location of boundary stones every mile along the perimeter of the District of Columbia.

Map from 1906 shows the location of boundary stones every mile along the perimeter of the District of Columbia.

The Georgetown Weekly Ledger noted that Banneker’s “abilities as a surveyor and an astronomer clearly prove that Mr. Jefferson's concluding that race of men were void of mental endowments, was without foundation."

That summer Banneker sent Jefferson, then Secretary of State, an ephemeris (a table of positions of heavenly bodies) along with a letter in which he challenged Jefferson's ideas about the inferiority of blacks. Jefferson forwarded the ephemeris to the Marquis de Condorcet, secretary of the Académie des Sciences in Paris.

In his letter, Banneker urged Jefferson and other whites “to wean yourselves from those narrow prejudices which you have imbibed.” Throwing back at him the words he penned in the Declaration of Independence, Banneker criticized the Founding Father as a hypocrite for touting the inalienable rights of man “while detaining by fraud and violence so numerous a part of my brethren, under groaning captivity and cruel oppression . . .”

    Jefferson’s polite response, Aug. 31, admitted the possibility that African-Americans may possess an intelligence which slavery had suppressed. “(N)o body wishes more than I do to see such proofs as you exhibit, that nature has given to our black brethren, talents equal to those of the other colours of men, & that the appearance of a want of them is owing merely to the degraded condition of their existence both in Africa & America. I can add with truth that no body wishes more ardently to see a good system commenced for raising the condition both of their body & mind to what it ought to be . . .”

Nineteen years later Jefferson provided a very different view in a letter to American writer and French revolutionary Joel Barlow. In refusing the opinion of Henri Gregoire, a French revolutionary and abolitionist who had described the intellect of various black men, Jefferson recalled his exchanges with Banneker.

“The whole do not amount in point of evidence, to what we know ourselves of Banneker,” he wrote. “We know he had spherical trigonometry enough to make almanacs, but not without the suspicion of aid from Ellicott, who was his neighbor & friend, & never missed an opportunity of puffing him. I have a long letter from Banneker which shews him to have had a mind of very common stature indeed.”

Nevertheless, Banneker published 28 editions of his almanac. He lived alone, designing what may have been the first reverse mortgage, selling his property to the Ellicotts based on a mortuary table of his life expectancy.  On the day he was buried in 1806, his house and belongings, including his famed clock, were burned to the ground.

Small fence surrounds the restored NE 6 boundary marker. Most of the small monuments still exist, though a few have been moved purposely over the years.

Small fence surrounds the restored NE 6 boundary marker. Most of the small monuments still exist, though a few have been moved purposely over the years.



“Benjamin Banneker: 1731-1806.” Africans in America. Public Broadcasting System.  PBS online.  Acquired 9/5/2016.

“Benjamin Banneker: 1731-1806.”Brookhaven National Laboratory. Acquired 9/6/2016.

“Benjamin Banneker Memorial.” Washington Interdependence Council. Acquired 9/6/2016.

“Benjamin Banneker Biography.” Encyclopedia of World Biography.  Acquired 9/6/2016

Benjamin Banneker, 1791-1806. Ed. Dr. Scott W. Williams. Mathematics Department, State University of New York at Buffalo. Acquired 9/6/2016.

“Andrew Ellicott.” Wikipedia.  Acquired 9/8/2016.
Jefferson, Thomas. Letter to Joel Barlow.