The phenomenon began a few months earlier, with the publication of “Roots: The Saga of an American Family.” Released in the fall of 1976—during America’s Bicentennial—it was an overnight commercial and critical success. The book would spend more than four months on The New York Times bestseller list, sell more than 6 million copies, be translated into more than 35 languages and earn Alex Haley both a National Book Award and a Pulitzer Prize.

Born in 1921 and raised in Ithaca, New York, and Henning, Tennessee, Haley was the son of a homemaker mother and an academic father who taught at universities throughout the South. He spent the summers of his youth at the side of his grandmother, Cynthia Palmer, absorbing stories of his maternal bloodline, including snippets of a presumed-lost African language that had been passed down through the generations. Palmer traced her ancestors to the mid-18th century arrival of the “furthest-back” person in America, an African called “Toby” by his slave owners.

A talented, though indifferent, student, 18-year-old Haley bypassed college, and on the eve of World War II enlisted in the U.S. Coast Guard, where he would serve for the next 20 years. He turned to writing, eventually rising to become the Coast Guard’s chief journalist. After leaving the service, Haley began a successful freelance career, contributing pieces to Reader’s Digest, TIME magazine and even interviewing musician Miles Davis for the first issue of Playboy. An interview with Malcolm X led to an offer to ghost write the controversial civil rights leader’s memoirs, which Haley finished just weeks before Malcolm’s assassination. Published in 1965, “The Autobiography of Malcolm X” put Haley on the map, selling more than 6 million copies to date.

The inspiration for “Roots” came to Haley in an unlikely place. While visiting London’s British Museum in 1964, he was struck by the story of the Rosetta Stone, the multi-lingual slab that helped researchers crack the code of Egyptian hieroglyphics, opening a new window on a “lost” world. Curious to see if the African phrases passed down by his family could be used similarly to unlock his own family history, Haley set out a decade-long journey across America and Europe, visiting nearly 50 libraries and archives.

In an era when most African Americans assumed it was impossible to track down proof of their ancestor’s origins, which had been swept away by more than a century of slavery and racial persecution, Haley’s doggedness led to remarkable results. Work with a linguist revealed the family language to be Mandinka, spoken by the West African Mandingo people of the Gambia. Slave ship records placed the 1767 arrival of a ship called the Lord Ligonier in Annapolis, Maryland. Haley pieced together historical records to connect his lineage to a slave named Toby, who Haley believed was his ancestor who had arrived on that ship. Furthermore, a visit to the Gambian town of Juffure resulted in a meeting with the local “griot,” a traditional storyteller responsible for preserving the history of local families—a role not unlike that played by Haley’s grandmother, Cynthia. According to Haley, his research indicated that he was the great-great-great-great grandson of Kunta Kinte (who he speculated was given the slave name Toby after his arrival in Maryland), one of nearly 1.5 million Africans from the Senegambian region who had been swept up in the transatlantic African slave trade.

The resulting novel followed Kinte’s capture, his horrific journey to America on the “Middle Passage,” his refusal to accept his enslavement, his daughter Kizzy’s brutal separation from her family, grandson Chicken George’s attempts to buy his family’s freedom, and the post-emancipation hostilities that led Haley’s great-grandfather to settle in Henning, Tennessee. In the years following its release, Haley faced criticism from journalists and historians who questioned his historical methodology, in particular his depiction of Juffure, which was not the bucolic village portrayed in the book, but rather a vibrant port and bustling hub of the slave trade in which competing African tribesmen captured and sold men, women and children into bondage. Bristling at the challenges to his work, which also included charges of plagiarism, Haley defended “Roots,” which had been marketed as an historically accurate novel, but which Haley (somewhat confusingly) now began referring to as “faction.”

The controversy did little damage to book sales and plans were already underway for a television adaptation. Network executives, however, proved to be more than a little skittish. Concerned that a predominately white television audience would turn away from the violent depiction of slavery in Haley’s book, they cast high-profile white actors in beefed-up versions of characters in the novel (which had been told solely from the point of view of blacks). Bucking convention, the network also scheduled the miniseries to air on consecutive nights instead of weekly installments, hoping to minimize their financial risk in case audiences simply tuned out (or southern affiliates refused to air the show at all).

Their fears proved to be utterly unfounded. When the series premiered on Sunday, January 23, 1977, more than 28 million viewers watched the first episode. Word of mouth, positive reviews (and a massive winter storm along the East Coast) led to an increased daily uptick in viewership as the saga unfolded. The January 30 finale captivated more than 100 million Americans (more than half the country and nearly 85 percent of all television households), breaking all previous ratings records. It remains the third-most watched single episode of all time, trailing only the final episode of “M.A.S.H.” and the iconic “Who Shot J.R.?” episode of “Dallas.” For the first time, the story of black Americans—and the remarkable talent of black actors—was prominently featured on network television. The show featured a vast array of African American talent, from newcomer LeVar Burton (still a teenager when he was cast as young Kunta Kinte) to O.J. Simpson and Maya Angelou in small roles. When “Roots” was re-aired the following year, it again captured the audience’s attention, as did a 1979 sequel that followed Haley’s descendants into the 20th century.

The cultural impact of “Roots” was immediate. Critics and journalists lauded the series’ frank depiction of slavery, and the resulting (albeit difficult) conversations between black and white Americans about a previously taboo subject matter. Civil rights leader and historian Roger Wilkins wrote in The New York Times that the program’s importance was comparable to the Montgomery Bus Boycott and the Selma-to-Montgomery March of 1965, and credited the show with upending centuries of racial stereotypes.

The mere word “roots,” previously associated with plant life, took on a new meaning as millions of Americans became inspired to search for their own ancestors. Today’s multi-billion dollar genealogy industry, which runs the gamut from TV shows to websites and companies offering up DNA-backed genetic “maps,” may not have existed without “Roots.” Almost overnight, the tracing of bloodlines, once seen as the privilege of the rich, was suddenly in vogue. And Americans took advantage of many of the tools Haley had used; libraries across the country noted a significant uptick in visitors across all racial and ethnic lines and inquiries for genealogical records at the National Archives increased by a staggering 300 percent.

America’s educational system saw an immediate impact, as well. The nation’s first collegiate African American studies program had been created at San Francisco State University just a decade earlier, in 1968, and it had been less than a year since locally-commemorated black history weeks had been expanded into today’s Black History Month. But in the aftermath of the television broadcast, more than 250 colleges and universities began offering courses on “Roots” and the history of slavery. And, like so many cultural events today, “Roots” inspired a baby-naming boom, with an increase in newborns receiving ethnic and African-inspired names.

Today, nearly 40 years after “Roots” swept the nation, its impact is still keenly felt. Its legacy encompasses everything from an annual Maryland festival honoring the memory of Kunta Kinte, to call-outs in hit rap songs and the opening scene of the Broadway musical “The Lion King.” In the aftermath of the tumultuous 60s and in the shadow of the civil rights movement, it changed the way many Americans looked at themselves—and each other—forever. It started a conversation, which in these still-fractious times, may be as necessary and critical as ever.