The film's working title was The White Piano. The title card on the viewed print reads: "A Drama of Real Life from the Reader's Digest, the Louis de Rochemont Production of Lost Boundaries." The film opens with a shot of the Brackett home in the fictional town of Keenham, New Hampshire, and a voice-over narration alluding to a legend that haunts the mansion. The film ends with a voice-over narration which states that the "Carters" still live in Keenham and "Scott Carter" is still the town physician. The character of Scott Carter was based on Dr. Albert C. Johnston, a black radiologist, who graduated with honors from the University of Chicago's Rush Medical School and passed as white in the 1930s. Johnston's black ancestry was disclosed when the United States Navy refused him a commission in 1940 because he admitted to being part black. Johnston continued to work in Keene, New Hampshire (which was called Keenham in the film) until the mid-1960s, when he moved to Kauai, Hawaii with his wife, Ihyra Baumann, who was of mixed parentage. He died in Honolulu on 23 Jun 1988 at the age of eighty-seven. As depicted in the film, Johnston's son, Albert, Jr., became a composer and wrote songs for this picture. The HR review of the film stated: "It is seldom written about, yet it is estimated that some 8,000,000 Negroes accomplish the deception [of 'passing' as whites] successfully," but that statistic has not been verified by any contemporary or modern source.
       According to one modern source, the idea for the film began when, while in his home town in New Hampshire, producer Louis de Rochemont met a light-skinned student (presumably Albert C. Johnston, Jr.), who confessed to having recently learned of his black ancestry. De Rochemont reportedly took the story to Reader's Digest, where it was written into a magazine article (and later a book) by William L. White. The same source states that Fredi Washington, who had co-starred in Universal's 1934 film about "passing," Fanny Hurst's Imitation of Life (see AFI Catalog of Feature Films, 1931-40; F3.2105), interviewed for a role in the film. Lost Boundaries marked the screen acting debut of Mel Ferrer (1907--2008), who previously had worked in Hollywood as a director and dialogue director.
       This film also marked the screen debut of Reverend Robert A. Dunn, an Episcopal clergyman from Portsmouth, New Hampshire. As reported in a NYT article, de Rochemont, who had a producing contract with M-G-M, was forced to produce the film independently after M-G-M canceled the project because of economic restrictions, and because the studio was planning two other films "dealing with other Negro questions": Intruder in the Dust (see above) and Stars in My Crown (see below).
       The name of the film's production company, RD-DR Corp., was an acronym for Reader's Digest--de Rochmont. De Rochemont was known for creating (along with Roy E. Larsen of Time, Inc.) the popular March of Time newsreel series, which won an Academy Award in 1936. In a 15 Feb 1948 memo to de Rochemont from scenarist Charles "Cap" Palmer included in the MPAA/PCA files at the AMPAS Library, Palmer states that he tried to "handle the story so that it avoids the pitfall of becoming a clinical study of the negro problem, and becomes a story of a guy, with the hell of a universal human problem." Scripts in the Charles Palmer Collection at the AMPAS Library reveal that Palmer's original ending showed "Shelley" standing alone on the green outside the church as her family attends services inside. A production note written by Palmer states that he wrote this ending to avoid "any peaches-and-cream feeling of a completely happy ending on a problem which is still unsolved generally."
       On 18 Nov 1949, RD-DR Corp. and Film Classics filed a federal lawsuit against Atlanta, Georgia after city censor Christine Smith banned all screenings of Lost Boundaries because of its racial theme. As noted in Var, Smith's decision was in accordance with a city ordinance that empowered her to bar any picture which would "adversely affect the peace, health, morals and good order of the city." As reported in Newsweek, in Oct 1949, local censor Lloyd T. Binford banned the film in Memphis theaters, giving the reason: "In passing as white the Negro doctor in the film had slurred his own race by proving himself 'an impostor and a liar.'" Citing the First and Fourteenth Amendments, former Justice Samuel Rosenman, the prosecuting attorney in the Atlanta case, stated in Nov 1949 trade papers that he hoped the suit would show deprivation of freedom of expression without due process of law, thereby testing the constitutionality of all censorship of motion pictures prior to public showing. As reported in DV, during the 6 Feb 1950 opening arguments in the U.S. district court, Assistant City Attorney J. M. B. Bloodworth, arguing the censors' side, alluded to a 1916 U.S. Supreme Court decision that films, as "spectacles," do not come under the First Amendment. Rosenman responded: "Films are no longer a spectacle but a medium of information and opinion, as much or more than they are mere amusement. Our interests go beyond those of my client and of the motion picture industry. They should be of concern to all Americans interested in their freedom." The case eventually went before the Fifth Circuit Court of Appeals, where the Atlanta censor's decision was upheld. In Oct 1950, the U. S. Supreme Court refused to hear an appeal of the case.
       According to HR, this film, which was shot in Massachusetts, Portsmouth, NH and Harlem, NY, won best scenario for 1949 at the Cannes film festival. Additionally, the film marked Richard Hylton's screen debut.