Benjamin Banneker, the Black Mathematician Who May Have Saved Washington, D.C.

Many people who have a passing familiarity with Washington, D.C. know it was originally styled after famous European capitals by architect Pierre Charles L’Enfant, then completed by Andrew Ellicott after L’Enfant was given the boot in 1792. Too few tourists and history fans, however, know that our nation‘s capital might have been a very different place if not for the surveying work of Benjamin Banneker—a highly accomplished mathematician, astronomer, and scholar who challenged Thomas Jefferson and his peers to recognize African-American achievement when it was right under their noses (and feet).

Benjamin Banneker was born November 9, 1731, in Baltimore County, Maryland, to Robert and Mary Banneker. While scholars still debate almost all the specifics of his background and early life, the most popular story suggests both sides of his family were enslaved. Although records are scarce, it‘s said that Benjamin’s maternal grandmother, a white woman named Mollie Welsh, was falsely convicted of theft in England and sentenced to indentured servitude in the colony of Maryland (not an uncommon practice at the time). After earning her freedom, she rented land in Baltimore County and purchased two enslaved people to help farm it. Several years later, after the farming operation was established, she freed both men.

One of them, who is said to have been abducted from a royal family in Africa earlier in his life, displayed a keen interest in astronomy and other scientific subjects. He was called Bannake or Bankka, and Mollie Welsh married him, violating a law that forbid marriage to enslaved people. Later, their daughter Mary and her husband—a Guinean man who had been enslaved, baptized with the name Robert, and then freed—chose to adopt the surname Banneker at the time of their own marriage. Just a few years after regaining his freedom, records show that Robert was able to purchase a 100-acre farm (possibly the same one his mother-in-law rented), where his family would live out much of their lives and where his son’s scholarship would bloom.

Banneker‘s Beginnings

Benjamin Banneker grew up as one of only 200 free African Americans among 13,000 whites and 4000 enslaved people in Baltimore County. His experience with formal instruction was limited to a brief stretch in a one-room Quaker schoolhouse that taught both Black and white students, but he was a keen study from his earliest years. Perhaps with his doting grandmother Mollie’s help, he learned to read and soon became especially interested in mathematics and mechanics, often performing calculations and experiments on his own.

Once he was old enough to work on the family farm, Banneker settled into a lifestyle that combined this work with scholarly achievement. After his father’s death when Banneker was 27, he continued running the farm with his mother and sisters. The horses, cows, garden, and multiple beehives he kept enabled a simple, comfortable life for the family, according to one 19th-century account presented to the Maryland Historical Society. Using crop rotation and irrigation techniques that wouldn’t catch on in the U.S. for many decades, he also raised profitable tobacco crops that were sold alongside his produce in the Ellicott family’s store. Taking heed of food shortages during the Revolutionary War, Banneker also swapped tobacco out for wheat to help feed American soldiers.

Throughout his life, biographer Elizabeth Ross Haynes wrote in 1921, Banneker “found time to study all the books which he could borrow.” He became well-versed in topics throughout the sciences and humanities. The 19th-century account presented to the Maryland Historical Society remembered Banneker as “an acute observer, whose active mind was constantly receiving impulses from what was taking place around him.”

For example, in a rather illustrative 1797 journal entry, Banneker wrote:

“Standing at my door I heard the discharge of a gun, and in four or five seconds of time, after the discharge, the small shot came rattling about me, one or two of which struck the house; which plainly demonstrates that the velocity of sound is greater than that of a cannon bullet.”

Some historians have speculated that Banneker’s many childhood lessons with his grandmother Mollie, who may have gained a sophisticated understanding of astronomy from Bannake, could have fostered his particular expertise with the subject. However, it was his prowess with mathematics for which he first became renowned throughout Baltimore County, according to a 1912 article. As word spread of his exceptional skills, far-away scholars began sending Banneker complex mathematical problems, and they continued to do so throughout his life. Banneker reportedly always solved them, often responding in verse and with a fresh problem.

As a young man, Banneker also gained fame and admiration for miles around due to one of his earliest known mechanical feats: building a working clock almost entirely out of wood from scratch. It may have been the first clock ever assembled completely from American parts, according to Haynes (although other historians have since disputed this). Banneker reportedly had only a borrowed pocket watch to use for reference on clockwork mechanisms, while his wooden version contained functioning, carved-to-scale components. The clock continued working until a few days after Banneker’s death, when a fire destroyed his cabin home and many of its contents—clock included.

A Mind for Mechanisms

However, Banneker’s accomplished scholarship remained mostly unknown outside the region until he encountered the Ellicott family. In 1772, the Ellicotts purchased the land next door to Banneker’s and began building new gristmill facilities there. Banneker’s fascination with the mill’s mechanics made him a frequent visitor to the site. In keeping with their Quaker traditions, the Ellicotts were adamant proponents of racial equality, and they collaborated with Banneker as well as encouraged wider application of—and recognition for—his unique skills.

George Ellicott, a close friend of Banneker’s for decades, was himself a student of astronomy and eagerly shared both his resources and queries with his neighbor. Banneker took great advantage of the borrowed tools and books in performing exquisite astronomical calculations, such as predicting a solar eclipse nearly to the exact moment in 1789. He also began building the foundations for several atlases and technical treatises he’d release in the decades before his death. In 1791, George’s cousin, Major Andrew Ellicott, gave Banneker a national stage, after Andrew had gone to George requesting help with a new job. George, being otherwise busy, suggested Banneker‘s assistance. The job was surveying land along the Potomac River for what would soon be the nation’s capital, Washington, D.C.

The plans for the city were laid out by French architect and engineer Pierre Charles L’Enfant, who volunteered for service in the American Revolution’s Continental Army and was hired for the project by George Washington in 1791. Before long, however, tensions mounted over the direction and progress of the project, and when L’Enfant was fired in 1792, he took off with the plans.

But, according to legend, the plans weren’t actually lost: Banneker and the Ellicotts had worked closely with L’Enfant and his plans while surveying the city’s future site. Banneker had actually committed the plans to memory and could redraw the full blueprint, down to the street grid, major buildings, and open spaces. Some historians argue, however, that Banneker had no involvement in this part of the survey at all, instead saying that Andrew and his brother were the ones who recreated L’Enfant’s plan. It‘s an intriguing myth, but it may only be that.

Sparring with Thomas Jefferson

Yet Banneker’s valuable contributions to the project drew attention, and set the stage for later correspondence with Thomas Jefferson. During the project, the Georgetown Weekly Ledger made public note of Banneker as “an Ethiopian, whose 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.”

In 1791, Banneker had finished his “painstakingly calculated ephemeris,” or table of the position of celestial bodies, which he would publish alongside charts, literature, and humanitarian and political essays in six almanacs with 28 editions in the following six years. Upon its initial completion, he first sent a copy of the ephemeris to then-secretary of state Thomas Jefferson, along with a famously direct, yet perfectly polite, letter challenging Jefferson’s opinion that African Americans bore an innate intellectual disadvantage compared to white Americans [PDF]. Among other things, Banneker observed:

“I have long been convinced, that if your love for yourselves and for those inestimable laws, which preserved to you the rights of human nature, was founded on sincerity, you could not but be solicitous that every individual ... might with you equally enjoy the blessings thereof, neither could you rest satisfied [short of] their promotion from any state of degradation, to which the unjustifiable cruelty and barbarism of men may have reduced them.

Sir, I freely and cheerfully acknowledge that I am of the African race ... and it is under a sense of the most profound gratitude to the supreme ruler of the Universe, that I now confess to you, that I am not under the state of tyrannical thraldom, and inhuman captivity to which many of my brethren are doomed, but that I have abundantly tasted of the fruition of those blessings, which proceed from that free and unequalled liberty, with which you are favored, and which, I hope you will willingly allow, you have received from the immediate hand of that being ... [and] that the present freedom and tranquility which you enjoy, you have mercifully received, and that it is the peculiar blessing of heaven.”

Jefferson’s letter in response was significantly shorter than Banneker’s, and not without traces of the mindset Banneker sought to defeat. But it also documented the scholar’s triumph in gaining some respect for his accomplishments, and in helping to dislodge certain prejudices from the minds of the era’s most learned men.

On August 30, 1791, Jefferson wrote:

“SIR,
I THANK you, sincerely, for your letter of the 19th instant, and for the Almanac it contained. No 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 colors of men ; and that the appearance of the want of them, is owing merely to the degraded condition of their existence, both in Africa and 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 and mind, to what it ought to be, as far as the imbecility of their present existence, and other circumstances, which cannot be neglected, will admit.

I have taken the liberty of sending your Almanac to Monsieur de Condozett, Secretary of the Academy of Sciences at Paris, and Member of the Philanthropic Society, because I considered it as a document, to which your whole color had a right for their justification, against the doubts which have been entertained of them.

I am with great esteem, Sir, Your most obedient Humble Servant,
THOMAS JEFFERSON.”

The discrimination African Americans suffered from Jefferson and other bigwigs is well documented, and Banneker’s brave, considered opposition to it stands forever among his many admirable achievements.

Records suggest that lower-profile white Americans belittled and questioned his achievements as well. Despite the many pushbacks he withstood, however, Banneker remained curious and generous of spirit. According to A Sketch of the Life of Benjamin Banneker, “his equilibrium was seldom disturbed by the petty jealousies and inequalities of temper of the ignorant people ... with whom his situation obliged him frequently to come in contact.”

Benjamin Ellicott, who prepared extensive notes on Banneker’s life for the Maryland Historical Society, remembered him as such in a letter:

“Although his mode of life was regular and extremely retired, living alone, having never married,--cooking his own victuals and washing his own clothes, and scarcely ever being absent from home, yet there was nothing misanthropic in his character … [He was known as] kind, generous, hospitable, humane, dignified and pleasant, abounding in information on all the various subjects and incidents of the day; very modest and unassuming, and delighting in society at his own home.”

Given Banneker’s wide-ranging interests and enthusiasm, then, it‘s fitting that a variety of parks, schools, awards, streets, businesses, and other public and private institutions and facilities all bear his name today. Admirers can learn about the accomplished scholar at Benjamin Banneker Park in Washington, D.C., at Baltimore‘s Benjamin Banneker Historical Park and Museum, or at the Banneker-Douglass Museum in Annapolis, Maryland. Or, visitors can follow in his footsteps by exploring their passions and hobbies at community centers named for Banneker in Washington, D.C., Bloomington, Indiana; and Catonsville, Maryland. It seems possible, however, that the man himself might have been most fond of—or, at least, a very frequent visitor to—Maryland’s own Banneker Planetarium.

A version of this story ran in 2016; it has been updated for 2023.