"When voters cast ballots for state representatives last fall, millions of Americans essentially had no choice: In 42 percent of all such elections, candidates faced no major party opponents.

Political scientists say a major reason for the lack of choices is the way districts are drawn — gerrymandered, in some cases, to ensure as many comfortable seats as possible for the majority party by creating other districts overwhelmingly packed with voters for the minority party.

'With an increasing number of districts being drawn to deliberately favor one party over another — and with fewer voters indicating an interest in crossover voting — lots of potential candidates will look at those previous results and come to a conclusion that it’s too difficult to mount an election campaign in a district where their party is the minority,' said John McGlennon, a longtime professor of government and public policy at the College of William & Mary in Virginia who has tracked partisan competition in elections."