The first laws criminalizing marriage and sex between whites and non-whites were enacted in the colonial era in the colonies of Virginia and Maryland, which depended economically on slavery. At first, in the 1660s, the first laws in Virginia and Maryland regulating marriage between whites and black people only pertained to the marriages of whites to black (and mulatto) enslaved people and indentured servants. In 1664, Maryland criminalized such marriages—the 1681 marriage of Irish-born Nell Butler to an enslaved African man was an early example of the application of this law. The Virginian House of Burgesses passed a law in 1691 forbidding free black people and whites to intermarry, followed by Maryland in 1692. This was the first time in American history that a law was invented that restricted access to marriage partners solely on the basis of "race", not class or condition of servitude. Later these laws also spread to colonies with fewer enslaved and free black people, such as Pennsylvania and Massachusetts. Moreover, after the independence of the United States had been established, similar laws were enacted in territories and states which outlawed slavery.