Essay 17

a) One trend in the graph is that the percent of southern state seats in the house held by democrats has gone down as shown below.
b) Incumbency advantage led to the election of more democratic house members and less presidents because there were democrats in the house before 1948 and with the incumbency advantage they could more easily win seats as opposed to presidents who usually lacked incumbency advantage. Differences between state and national parties also contributed because they were largely separate entities and therefore voters who liked democrats in their state did not necessarily like them for the presidency.
c) In the modern day, social conservatives are now more associated with republicans whereas they used to be associated with democrats. More women have moved to become democrats in recent decades. Also, labor union workers have moved and are now mostly democrats.

http://apcentral.collegeboard.com/apc/public/repository/ap10_us_govt_politics_scoring_guidelines.pdf