MacBride worked for the Wall Street-based law firmWhite & Case for several years before opening a small practice in Vermont. By the mid-1970s, MacBride had relocated to Virginia and was no longer practicing law full-time.
Writing and television producing career
MacBride inherited Lane's estate including rights to the substantial Ingalls-Wilder literary estate, including the "Little House on the Prairie" franchise. He is the author of record of three additional "Little House" books, and began the "Rocky Ridge Years" series of children's novels, describing Lane's Ozark childhood. He published two books on constitutional law – The American Electoral College and Treaties versus the Constitution, as well as a Libertarian Party manifesto – A New Dawn for America: The Libertarian Challenge. In the 1970s, MacBride co-created the television series Little House on the Prairie and served as a co-producer for the show.''
MacBride was the treasurer of the Republican Party of Virginia in 1972 and one of the party's electors when Richard Nixon won the popular vote for his second term as President of the United States. MacBride, however, as a "faithless elector," voted for the nominees of the Libertarian Party – presidential candidate John Hospers and vice-presidential candidate Tonie Nathan. In doing so, MacBride made Nathan the first woman in U.S. history to receive an electoral vote. Political punditDavid Boaz later commented in Liberty magazine that MacBride was "faithless to Nixon and Agnew, anyway, but faithful to the constitutional principles Rose Wilder Lane had instilled in him."
1976 presidential campaign
After casting his electoral vote in 1972, MacBride instantly gained favor within the fledgling Libertarian Party, which had only begun the previous year. As the Libertarian presidential nominee in 1976, he achieved ballot access in 32 states; he and his running mate, David Bergland, received 172,553 popular votes by official count, and no electoral votes. His best performance was in Alaska, where he received 6,785 votes, or nearly 5.5%. In his campaign the issues that he supported included a free market system, a return to the gold standard, the abolition of the Federal Reserve, an end to corporate welfare, the abolition of the FCC, a foreign policy of non-interventionism, and abolishing all victimless crimes.
MacBride rejoined the Republican Party in the 1980s and helped establish the Republican Liberty Caucus, a group promoting libertarian principles within the Republican Party. He chaired this group from 1992 until his death in 1995.
Death
MacBride died of heart failure on March 5, 1995. A controversy ensued upon his death when the local library in Mansfield, Missouri, contended that Wilder's original will gave her daughter ownership of the literary estate for her lifetime only, and that all rights were to revert to the Laura Ingalls Wilder Library after her death. The ensuing court case was settled in an undisclosed manner, but MacBride's heirs retained the rights. In an obituary for MacBride, David Boaz wrote, "In some ways he was the last living link to the best of the Old Right, the rugged-individualist, anti-New Deal, anti-interventionist spirit of Rep. Howard Buffett, Albert Jay Nock, H. L. Mencken, Isabel Paterson, and Lane."