Benjamin Banneker was born a free black man in Virginia in 1731 – his mother was also a free black, his father a former slave now free. Largely self-educated, in 1791 he was a member of the team that surveyed the boundaries of the newly declared District of Columbia. His primary duty was to take astronomical observations to ascertain the exact locations of the various points the survey visited.
The following year, Banneker turned his skill at astronomy to creating an ephemeris, which he then published in an almanac. The almanac sold well enough that he continued to make them annually until 1797. He became a man of some note, and was a regular correspondent of President Thomas Jefferson, with whom he argued about slavery and other political issues. He died after retiring from public life, aged 74.