Sentence:  Old attitudes are held more tenaciously in the <WSD>Tidewater</WSD> than the Piedmont ; 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 coastal plain of the South: eastern parts of Virginia and North Carolina and South Carolina and Georgia