This essay explains, in three topics, when, where, and how America’s endogamous color line was invented. The Years Before the Color Line was Invented describes colonial life before the turn of the eighteenth century. It shows that colonists of African and European ancestries mingled and married within each of the three rigid social classes: forced laborers, shopkeepers/artisans, and planters. The Transition Period narrates events in and around the Chesapeake leading up to the 1691 law, the first in history to outlaw Afro-European intermarriage. The Spread of the New Color Line describes the aftermath as punishments for violating the 1691 law became increasingly harsher, and similar laws were passed in subsequent generations throughout British North America.