THIS IS A BLOCK OF 8 STAMPS AS PICTURED. ~ On February 1, 1978 in Washington, DC., the USPS issued the first stamp of the Black Heritage Series, honoring Harriet Tubman, known as the Moses of her people. A former slave, she escaped bondage by fleeing to Pennsylvania. However, she returned to the South at least 19 times in order to help more than 300 slaves escape to freedom.