The film's promotion said that it was based on a "true story", but while the inspiration for some elements was derived from the notorious serial killer, Ed Gein, who committed his crimes in Wisconsin in the 1950s, the bulk of the story is predominantly fictional, with the assertion of being a "true story", in reality, functioning as a commentary on the manipulation of the press of the era. Media and political "spin" routinely covered up the truth of what was happening in and around the major events of the time, promoting often entirely false narratives. It was also a response to the callous detachment of mainstream journalism as it reported the horrors of the day. Thus, framing the film as "true" was a wink at the audience to consider the source and never take anything at face value.
The Texas Chainsaw Massacre was Tobe Hooper's third feature film, for which he was writer, director, composer, editor and cinematographer. For the production, he was working with a very tight budget of $140,000 ($700,000 adjusted for inflation). With the principal expenses focused on equipment rentals, the cast and crew were required to work 16 hour days, seven days a week, in order to maximize equipment usage. The entire film was shot in Texas, utilizing mostly unknown local talent for the cast.
Filming conditions were brutal during the shoot, with temperatures routinely topping 100°F, and no AC for any of the interior scenes. With practical effects utilizing actual animal carcasses for props and set dressings, in varying states of decay, including smearing real blood on the walls, plus the inability to launder costumes and masks, especially those used by Leatherface, for fear of losing continuity, the experience on set must have been exceptionally putrid! It was an experience that made many of the cast and crew "hate" Hooper by the end of the production, requiring years for some to fully forgive the trauma of being on that set.
Conceptually, the film is notable for introducing the trope of using power tools for murder weapons, with Hooper having conceived of the chainsaw angle while waiting in a long line at a hardware store one day, musing on what might be an effective way to "thin the queue". The set and setting for the story had been lingering in Hooper's mind for a few years before, dealing with the ideas of isolation, the woods, and darkness. As previously mentioned, notorious serial killer, Ed Gein was a key inspiration for the main characters, and Gein would be a recurring reference point in the genre in subsequent years, with films like Silence of the Lambs also tapping into that history.
Gunnar Hansen, who played Leatherface, in order to better represent his character, spent time in the classrooms of learning disabled children as a way to get into the mindset of someone who is not able to communicate properly with other people. On set, Hooper would coach him to ensure that he would be consistent in his use of gibberish, though Hooper would make sure Hansen understood the literal intent of what he was trying to say. This attention to detail helped to lend the character a humanizing depth, something that actually made him all the more horrifying by grounding him in a sense of plausibility.
While Hooper had actually refrained from using an excessive amount of gore, in the hopes of landing the film a PG rating, the film board still slapped it with an R, but that didn't seem to hurt the box-office returns, which given the modest investment, were ultimately spectacular. Though it was certainly a commercial hit, it also encountered significant backlash in some markets, with certain countries banning the film, outright. Critics were also split on its merits, with some finding its brutality simply too hard to tolerate, questioning the ethics of the producers, while others were impressed with the acting and the films technical execution.
The film became the next in line to redefine the horror genre, following Night of the Living Dead, as an astute social commentary smuggled in under the guise of low-brow exploitative entertainment. Its rendering of a perverse backwoods family resonates even today, maybe especially today, in the era of "MAGA". It shows this backwoods family living in a state of grotesquely diminished and distorted ethics and values, morphed into some kind of monstrous assault on morality. In the context of the film, they're discards from a capitalistic post-industrial manufacturing wasteland. They worked at a slaughterhouse, in an impersonal industrialized factory dedicated to the process of dehumanizing both the product and the people who worked there. In a similar way, the MAGA crowd are equally disenfranchised and dissociated from normal perceptions of right and wrong. In that sense, The Texas Chainsaw Massacre is an unsettling prediction of the decline of middle American values and ethics. Others have even interpreted it as a pro-vegetarian salvo, with its grizzly depiction of slaughter and meat being considered some of the best promotional material for vegetarianism around. Some have criticized the films abuse of women, with studies actually using the film as a test of male empathy. Whatever your interpretation, it's clear the movie has a depth of meaning that can be perceived from a variety of angles.
Ultimately, it has remained as a landmark in the genre of horror film making, establishing a number of different tropes in terms of how violence can be depicted and interpreted on screen. Personally, I consider it one of the essential films in the genre from that era, along with George Romero's previously mentioned Night of the Living Dead, and Sam Raimi's Evil Dead. I think those three films have a distinct hold on the reigns when it comes to pushing boundaries and setting standards in the domain of blood & guts film making.