Sentence:  And in this <WSD>white belt</WSD> borderland between the black belt South and the free labor North, few whites lamented that the slave drain continued to thin blacks out of their area and to thicken the institution in the most southern South, repeating the turtle-slow erosion of slavery in the most southern North between 1776 and 1830 
Meaning of the word marked with <WSD> tags:  A region in which the majority of residents are white.