February 2, Illinois
March 2, Texas
May 4, Indiana
May 4, North Carolina
May 4, Ohio
May 11, Nebraska
May 11, West Virginia
May 18, Arkansas
May 18, Kentucky
May 18, Oregon
May 18, Pennsylvania
May 25, Idaho
June 1, Alabama
June 1, Mississippi
June 1, New Mexico
June 8, Arkansas, if run-off from earlier primary needed
June 8, California
June 8, Iowa
June 8, Maine
June 8, Montana
June 8, Nevada
June 8, New Jersey
June 8, North Dakota
June 8, South Carolina
June 8, South Dakota
June 8, Virginia
June 22, Mississippi, if run-off from earlier primary needed
June 22, North Carolina, if run-off from earlier primary needed
June 22, South Carolina, if run-off from earlier primary needed
June 22, Utah
June 29, South Dakota, if run-off from earlier primary needed
July 13, Alabama, if run-off from earlier primary needed
July 20, Georgia
July 27, Oklahoma
August 3, Kansas
August 3, Michigan
August 3, Missouri
August 5, Tennessee
August 10, Colorado
August 10, Connecticut
August 10, Georgia, if run-off from earlier primary needed
August 17, Washington
August 17, Wyoming
August 24, Alaska
August 24, Arizona
August 24, Florida
August 24, Oklahoma, if run-off from earlier primary needed
August 28, Louisiana ("first party")
September 14, Delaware
September 14, District of Columbia
September 14, Maryland
September 14, Massachusetts
September 14, Minnesota
September 14, New Hampshire
September 14, New York
September 14, Rhode Island
September 14, Vermont
September 14, Wisconsin
September 18, Hawaii
October 2, Louisiana ("second party")
note: states in bold involve races for the U.S. Senate; all seats in the House of Representatives of course are up anyway