What protestant denominations swept up large numbers of free and enslaved blacks as well as white frontier families in the early nineteenth century?

Answer

The Methodists and Baptists denominations.

Explanation

The Methodists and Baptists denominations' beliefs and preaching, which were quite new around the early nineteenth century, were widely accepted by black slaves and white slave-owners, created a great revival, inspired new movements, and the founding of schools and seminaries, especially in the South.