In the United States party caucuses and primary elections are essential to choosing presidential candidates. This calendar lists currently scheduled presidential primaries and caucuses leading up to the national 2004 election. (Caucuses are in italics.)

In this context a "caucus" generally refers to a statewide gathering of each party's local political activists during the presidential nomination process. The purpose of the caucus system is to indicate, through delegate choice, which presidential candidate is preferred by each state party's members. Primaries serve a similar function, but they are direct electoral contests held to choose a political party's candidate for a particular public office. Depending on state law, voters cast ballots for the presidential candidate they prefer or for delegates who are "pledged" to support that presidential candidate at the party's convention.

January 19
Iowa

January 27
New Hampshire

February 3
Arizona
Delaware
Missouri
Oklahoma
South Carolina (Demokraten)
New Mexico (Demokraten)
North Dakota

February 7
Michigan (Demokraten)

February 8
Maine (Demokraten)

February 10
Tennessee
Virginia
District of Columbia (Republikaner)

February 14
District of Columbia (Demokraten)
Nevada (Demokraten)

February 17
Wisconsin

February 24
Utah (Demokraten)
Hawaii
Idaho

March 2
California
Connecticut
Georgia
Maryland
Massachusetts
New York
Ohio
Rhode Island
Vermont
Washington
Minnesota

March 9
Florida
Louisiana
Mississippi
Texas

March 13
Kansas (Demokraten)

March 16
Illinois

March 20
Alaska (Demokraten)

April 13
Colorado (Demokraten)

April 27
Pennsylvania

May 4
Indiana
North Carolina

May 6-8
Wyoming (Republikaner)

May 11
Nebraska
West Virginia

May 15
Wyoming (Demokraten)

May 18
Arkansas
Kentucky
Oregon

May 25
Idaho

June 1
Alabama
New Mexico
South Dakota

June 8
Montana
New Jersey

July 26 - 29
Democratic National Convention,
Boston

August 30 - September 2
Republican National Convention,
New York City