Sentence:  Old attitudes are held more tenaciously in the Tidewater than the <WSD>Piedmont</WSD> ; so that a line running down the length of the South marking the upper limits of tidewater would roughly divide the Old South from the new , but with , of course , important minority enclaves . 
Meaning of the word marked with <WSD> tags:  the plateau between the coastal plain and the Appalachian Mountains: parts of Virginia and North and South Carolina and Georgia and Alabama