2004 Presidential election results map. Red denotes states/districts won by Republican George W. Bush, and Blue denotes those won by Democrat John Kerry. Numbers indicate electoral votes allotted to the winner of each state.
Riding Bush's coattails, the Republicans picked up net gains of four Senate seats and three House seats. In the gubernatorial elections, neither party won a net gain of seats. Bush became the first President since Ronald Reagan in 1980 to see his party gain seats in both Houses of Congress during a Presidential election year. Republicans would not win another trifecta until 2016.
As of 2020, this is the last time the incumbent party retained control over the presidency and Congress after a single term. It is the only election cycle since 1928 in which a Republican trifecta was successfully maintained, as well as the first time since the 1950 and 1952 elections that the Republicans gained seats in consecutive elections.
Republicans gained a couple of seats in the House, mainly due to the 2003 Texas redistricting. Republicans won the national popular vote for the House of Representatives by a margin of 2.6 percentage points.[1]
Summary of the 2004 United States House of Representatives elections results
Eleven of the fifty United States governors were up for re-election, as were the governorships of two U.S. territories. The final results were a net change of zero between the political parties. The Democrats picked up the governorships in Montana and New Hampshire, but the Republicans picked up the ones in Indiana and Missouri.
In many states where if the following positions were elective offices, voters cast votes for candidates for state executive branch offices of Lieutenant Governor (though some were voted for on the same ticket as the gubernatorial nominee), Secretary of state, state Treasurer, state Auditor, state Attorney General, state Superintendent of Education, Commissioners of Insurance, Agriculture or, Labor, etc.) and state judicial branch offices (seats on state Supreme Courts and, in some states, state appellate courts).
Democrats took control of eight legislative chambers including the Washington Senate; the Oregon Senate, which was previously tied; both houses of the Montana legislature; both houses of the Colorado legislature for the first time since 1963; the North Carolina House of Representatives- which was previously tied; and the Vermont House of Representatives. Additionally, the Iowa Senate became tied after previously being controlled by the GOP before the election.[3]
The Democrats also regained the title of holding the most seats although their margin is a tiny fraction of 1 percent — a mere one seat at press time. Republicans won four legislative chambers.[4]
2 Republicans replaced by 
2 Democrats
