How can gerrymandering impact legislative elections

Gerrymandering only directly effects the House of Representatives and, as is pointed out, Maine and Nebraska’s Electoral College delegations. There have been proposals to have Michigan, Pennsylvania, and Virginia decide the Electoral College delegations in the same manner as Maine and Nebraska. However, had this happened prior to the 2012, even though Obama won the popular vote in all three states, due to gerrymandering, the majority of each of these states Electoral College delegations would have voted for Romney.