It happens regularly in states where one big city (think Chicago) comes to dominate politics
Which (as an aside) is why the One Man One Vote doctrine of elected representation as currently applied is bad. For example, before that doctrine Oklahoma had one State Senator per county. But because that was unequal representation of the individual voters (nevermind that the Senate was intended to represent the interests of local governments, much like the U.S. Senate was intended to represent the interests of each state), such representation was determined to be unconstitutional.