After three unsuccessful runs for Congress in the 1960s, Treen won his first election in 1972 to represent a U.S. House district that covered parts of Greater New Orleans and Acadiana.

During his single term as governor, Treen cut the state income tax and created a professional development program for teachers.

After leaving the governor's office, Treen continued to be politically involved in Louisiana, running for Congress and endorsing gubernatorial candidates as recently as 2008 before his death in 2009.

[2] In 1945, Treen graduated from the former Alcee Fortier High School in New Orleans, where his classmates included the subsequent political consultant and journalist Victor Gold.

[8] Treen warned at a rally that "Reconstruction of the South is far from being over" and that "the Democratic and Republican parties would reduce the laboring man to mere tools in a socialistic state.

Encouraged by friends, Treen launched a campaign for the U.S. House of Representatives to serve Louisiana's 2nd congressional district, based in New Orleans, against incumbent Democrat Hale Boggs.

[18] Following the 1970 United States Census, Louisiana's 2nd congressional district was reapportioned to exclude parts of Jefferson Parish with strong Republican support, including Treen's residence.

In a campaign tour in Minden, Treen said that Louisiana needed "true competition" in state government, or "a system in which two political parties operate on a continuing and permanent basis to examine and criticize each other's policies and programs."

[21] Later in 1972, Treen ran for the open Louisiana's 3rd congressional district seat vacated by conservative Democrat Patrick T. Caffery of New Iberia.

[24] In the 1974 midterm elections that happened nearly three months after the resignation of President Richard Nixon, Democrats added 49 seats to their House majority.

[26] Because he faced no opposition in the primary, scheduled for September 16, no votes were tabulated for his district in the general election on November 7, and Treen won reelection by default.

[33] While in Congress, Treen was part of a special committee that successfully amended the Outer Continental Shelf Lands Act of 1953 to allow states greater review of offshore drilling on the Gulf Coast.

[34] The amendment added the following text to the Small Business Act: "If loan applications are being refused or loans denied by such other department or agency responsible for such work or activity due to administrative withholding from obligation or withholding from apportionment, or due to administratively declared moratorium, then, for purposes of this section, no duplication shall be deemed to have occurred.

[43][44][42] Barely finishing in second place and the final qualifying spot for the general election was Louis Lambert, a Democratic member of the Louisiana Public Service Commission, with 20.74 percent of the vote.

[45] While Treen was most popular in the Greater New Orleans, Acadiana, and North Louisiana, Lambert had the strongest support among black voters and members of labor unions.

[42] One factor in black and labor voters' preferring Lambert, according to Howell Raines of The New York Times, was Treen's 1960 work for the Louisiana States' Rights Party.

Please keep it close so it can serve as a constant reminder of your solemn commitment to the people of this great state ..."[51] Treen entered office with Democratic Lieutenant Governor Robert L. Freeman (an Edwards floor leader during his two terms in the House), a Louisiana State Senate that had no Republican members, and Louisiana House of Representatives where Democrats had a supermajority.

[65] In 1982, Treen proposed a $450 million tax on petroleum and natural gas, to support preservation of coastal wetlands, as more was being understood about their critical role in protecting the coast.

[67] CWEL was defeated in the Louisiana House although it received approval from a majority of lawmakers; it fell twelve votes short of the required two-thirds needed.

[68] After the defeat of CWEL, Treen ordered a three percent reduction in state employment, with the goal of saving $12 million, far less than the environmental tax would have generated.

When a 1982 reform plan failed, Treen blamed LABI because the trade association would not compromise with the Democrats to secure a bill that could pass the legislature.

LABI director Ed Steimel declared the worker's compensation problem at the time to be the major roadblock to bringing new and expanded industries into the state.

[79] At a fundraiser in Thibodaux to celebrate his 55th birthday, Treen said that Edwards in 1980 "left a pile of unpaid bills and a stinking surplus of hazardous waste dumps.

[97] Addressing an increasing incarceration rate in Louisiana, Treen advocated crime prevention programs such as education, arts, and sports.

The same story reported that as a state legislator in the 1980s, Democratic candidate Mary Landrieu had given Tulane tuition waivers to a former campaign manager.

[105] Following the resignation of Representative Bob Livingston, Treen attempted a political comeback by entering the 1999 Louisiana's 1st congressional district special election on January 26, 1999.

[90] In 2007, Treen and Johnston wrote to then-President George W. Bush to request a presidential pardon of Edwards, who began a 10-year prison sentence in 2002 for corruption.

In an editorial following his death, The Times-Picayune of New Orleans said of Treen: "Louisianians will remember him as a sensitive, honorable and fair man who carried those qualities into the governor's office during his tenure from 1980 to 1984.

He played an important role in organizing U.S. House Republicans toward a conservative, reformist model in the late 1970s to help lay the groundwork for the Reagan presidency.

In November 2009, the St. Tammany Parish school board voted unanimously to dedicate the David C. Treen Instructional Technology Center, which opened in March 2010.