Presidential Elections/House of Representatives
While George W. Bush won the Presidential elections in 2004 with a clear win, in 2000 he got elected President with fewer votes cast for him than for his opponent, Al Gore. In the United States, voters do not elect the President, voters elect state delegates, and they vote collectively for the Presidency. In 2000, Florida's 25 electoral votes all went for Bush. In four Presidential elections (7.3% of all Presidential elections) the elected president did not receive the most votes.
The indirect vote is directly linked to not picking the one with the most votes as President, especially with the states' electoral votes also being cast as a block. Every time a race is truly very close, the chance exist that the runner-up runs straight into the White House due to the indirect nature of how we elect our President.
House of Representatives
Gerrymandering got its name from Massachusetts Governor Gerry, whose Jeffersonian party created an electoral district for the 1812 elections with extremely irregular boundary lines that looked like a salamander. Nowadays, the political parties in control constantly gerrymander the districts to skew the end result towards them winning as many seats as possible.