Shopkeepers, artisans, shipwrights, butchers, coopers, seamstresses, cobblers, bakers, carpenters, masons, and many other specialized crafts made up the middle class of seaport society. Wives and husbands often worked as a team and taught their children their skills to pass it on through the family. Many of these artisans and traders made enough money to create a modest life. Laborers stood at the bottom of seaport society. These poor people worked on the docks unloading inbound vessels and loading outbound vessels with wheat, corn, and flax seed. Many of these were African American; some were free, while others were enslaved. In 1750, blacks made up about 10 percent of the population of New York and Philadelphia. Hundreds of seamen worked as sailors on merchant ships, some of whom were African American.