Lowenthal, a long-term resident of [[Lake Charles]], [[Louisiana]], attended the University of Louisiana at Lafayette and [[Louisiana State University]] in [[Baton Rouge, Louisiana|Baton Rouge]] but graduated with degrees in [[English] and speech from [[Baylor University]] in [[Waco, Texas|Waco]], [[Texas]]. She worked as a [[radio]] and [[television]] announcer, owned a public relations agency, worked as a private counselor, and served on the Calcasieu Parish Police Jury prior to her election in 1979 to the state House of Representatives.<ref name=ourcampaigns/>
As a legislator, she authored numerous bills relating to the environment, the arts, health, education, family violence, taxation, juvenile delinquency, forced heirship, utilities, and women's issues. In 1983. she was named "Legislator of the Year" by the Louisiana Arts Council.<ref name=ourcampaigns>{{cite web|url=http://courcampaigns.com/CandidateDetail.html?CandidateID=21505|title=Lowenthal, Margaret W.|publisher=, ourcampaigns.com|accessdate=July 28, 2020}}material no longer on-line.</ref> She pushed for extra funds when Sam Houston High School in Lake Charles burned.<ref>{{cite web|url=http://kplctv.com/story/1372682/former-louisiana-legislator-dies|title=Former Louisiana Legislator Dies|publisher=KPLC-TV|location=[[Lake Charles]]|date=July 23, 2003|accessdate=July 12, 2015}}</ref>
In 1985, Representative Lowenthal got into a public dispute with her fellow [[Democratic Party|Democrat]], [[Victor Bussie]], the long-term president of the Louisiana [[AFL-CIO]]. While addressing the Lake Charles Optimist Club at its regular luncheon meeting, Lowenthal claimed that she had been told by an unidentified representative of [[Boeing]] that the firm had considered locating a manufacturing facility in Louisiana, but ultimately chose [[Mississippi]] because of Louisiana's unstable political climate and its longstanding problems with public education. Lowenthal said that she was told further by the Boeing representative that, "'As long as you have a man named Victor Bussie sitting in [[Baton Rouge]], calling the shots for labor, we don't need to be in your state.'" Her remarks were telecast over Lake Charles television.<ref name=problemwithbussie>{{cite web|url=http://www.leagle.com/decision/1988913535So2d378_1888/BUSSIE%20v.%20LOWENTHAL|title=Bussie v. Lowenthal|date=December 12, 1988|publisher=leagle.com|accessdate=July 29, 2020}}</ref>