So my question is, why did Virginia have such a conservative democratic party for so long? Was it because of its location in the tidewater and historic elite presence (guys like the cavaliers)? Was it a tradition in Jeffersonian democracy favoring the wealthy planters? Was it the military presence or the Byrd family's influence?
The Byrd organization was key here for sure. It's basis was not in the Tidewater region so much as the Southside (basically in the southern part of Hurt's district and the rural white parts of Forbes'). This region was for along time both the most conservative and the most Democratic, giving the best percentages in Virginia for Stevenson and JFK, but also Goldwater and Wallace. The military areas such as in Norfolk were actually somewhat more Republican and moderate than much of the state.
