1966 United States House of Representatives elections

• Alaska's at-large congressional district: four-term Democratic incumbent Ralph Julian Rivers was defeated by Republican State Senator Howard Wallace Pollock.
• Arizona's 3rd congressional district: sophomore Democrat George F. Senner Jr. was defeated by state legislator Sam Steiger.
• Arkansas's 3rd congressional district: lumber executive and Arkansas GOP chair John Paul Hammerschmidt defeated incumbent James William Trimble, becoming the first Republican member of Arkansas' congressional delegation since Reconstruction.
• California's 18th congressional district: onetime Olympic gold medalist Robert B. Mathias defeated seven-term Democratic incumbent Harlan Hagen.
• California's 25th congressional district: Charles E. Wiggins defeated incumbent Democrat Ronald B. Cameron.
• California's 33rd congressional district: Jerry L. Pettis defeated incumbent Kenneth W. Dyal.
• Texas's 7th congressional district: businessman and 1964 U.S. Senate candidate George H. W. Bush defeated Democratic challenger Frank Briscoe for the seat vacated by John V. Dowdy (whose district had been renumbered the second).
• Texas's 18th congressional district: Bob Price succeeded retiring Democrat Walter Edward Rogers by defeating Dee Miller.

Elections are listed by date and district.

Parties		Seats				Popular Vote
		1964	1966	Change	Strength	Vote	%	Change
	Democratic Party	295	248	47	57.0%	26,934,136	50.9%	6.2%
	Republican Party	140	187	47	43.0%	25,521,157	48.2%	5.8%
	Conservative Party	–	–	–	–	208,756	0.4%	0.3%
	Independent	–	–	–	–	85,641	0.2%
	Liberal Party	–	–	–	–	75,303	0.1%	0.1%
	Peace and Freedom Party	–	–	–	–	16,922	<0.1%
	American Independent Party	–	–	–	–	14,461	<0.1%
	Constitution Party	–	–	–	–	11,110	<0.1%
	Socialist Labor Party	–	–	–	–	5,771	<0.1%
	Independent-Socialist Party	–	–	–	–	3,502	<0.1%
	New Hispano Party	–	–	–	–	2,263	<0.1%
	People's Choice Party	–	–	–	–	1,299	<0.1%
	Socialist Workers Party	–	–	–	–	1,014	<0.1%
	Veteran Party	–	–	–	–	939	<0.1%
	Others	–	–	–	–	29,701	0.1%	0.1%
Total		435	435	0	100.0%	52,901,975	100.0%	——

Source: Election Statistics – Office of the Clerk

¹ One vacancy due to refusal of House to seat Adam Clayton Powell Jr. (D-New York)

House seats by party holding plurality in state   80+% to 100% Democratic   80+% to 100% Republican   60+% to 80% Democratic   60+% to 80% Republican   ≤ 60% Democratic   ≤ 60% Republican

6+ Democratic gain   6+ Republican gain   3-5 Democratic gain   3-5 Republican gain   1-2 Democratic gain   1-2 Republican gain   no net change

Florida redistricted to adjust for demographic changes; in addition to minor boundary changes a district was removed from northern Florida, and Broward County was broken out into its own district.[2]

Indiana redistricted for this election, election boundary changes forced two Republican incumbents into the same district while creating a new district that was won by another Republican.[2]

Maryland redistricted its at-large district into an 8th district around Montgomery County, managing to adjust boundaries so no existing incumbents were displaced.[2]