BRANSON, Mo. — Bestselling author Janet Dailey was a pioneer in the often-derided billion-dollar business of romantic fiction.

“She was in the forefront of Americanizing romance novels,” using “American settings, heroines, heroes, situations and sensibilities” in her work, explained Dr. Pamela Regis, professor of English at McDaniel College in Westminster, Md., and author of “A Natural History of the Romance Novel.”

Dailey, who died unexpectedly last week at age 69, was the first American to sell a manuscript to British romance publisher Harlequin in the mid-1970s.

“Janet Dailey paved the way more than anyone else for acceptance of American writers in contemporary romance,” St. Louis-based romance author Eileen Dreyer told me. “She was a darn good storyteller, and early on she was prolific. On top of that, she was unfailingly kind, generous and open.”

If you’re not familiar with the history of romance novels, you might not understand just what a difference Dailey’s books made. As Dreyer explained rather bluntly, “American writers were the first ones to have a heroine with a spine or a real occupation. In the old European romances, the heroine was a virginal idiot and the hero was a jerk.”

Dailey’s heroines were strong, independent, even feisty women and she set her books, like the immensely popular Calder series, in distinctly American settings, especially the West.

That modern-day Western setting became so popular that it’s considered a sub-genre of romances, Regis wrote in her history, which devotes a chapter to Dailey and the Americanization of the romance novel.

Dailey’s success ushered in the boom of romance publishing in the late ’70s and early ’80s as Simon & Schuster entered the field with Silhouette (later bought by Harlequin). Meanwhile, Dailey graduated from category romance to single title hardback fiction at HarperCollins, with more than 20 of her books making the New York Times Bestseller list.

Readers loved Dailey’s books;  325 million copies, translated into 19 languages, have sold around the world. Compare those numbers with Stephen King, whose sales are estimated between 300 and 350 million, or J.K. Rowling, with an estimated 350 to 450 million in sales.

She was “a tremendously talented writer,” said Sarah Wendell, co-founder of the Web site and author of “Everything I Know About Love I Learned from Romance Novels.” “Readers still treasure her books.”

One fan, Conetta Taylor, traveled from her home in Nixa, Mo., to Dailey’s funeral Thursday. “There was such a sense of realism in Janet’s books,” she told me. “They were inspirational.”

And she inspired future writers as well. “Janet Dailey introduced me to reading romances, and probably because of her, I have published 10 books,” said romance novelist Judy Baker.

But romance novels don’t get respect. “Romance is the most gendered form of fiction, written by women, for women (for the most part),” Regis explained to me. “Girls and women have always read across the gender divide — appreciating male protagonists and the sort of narratives that men like.”

Boys and men won’t cross that line, though. (Ever wonder why J.K. Rowling used her initials instead of her first name Joanne?) And it’s men who’ve been “the gatekeepers” of opinion until recently, Regis said. “They have written and edited book reviews, they have served as editors at major presses, and they have written the literary histories.”

Yet romance novels are big business, generating $1.4 billion in sales in 2012, according to Romance Writers of America. “This very old narrative form has simply taken over the fiction marketplace,” Regis said.

Dailey had the typical back story of many writers: She loved to read, her three older sisters told me. Their father died young and their mother was working, so the older girls would read to Janet or encourage her to “write” a story by drawing pictures so she’d stay quiet while they did their homework.

“By the time Janet was 10 or 12, she’d read every children’s book in the library so she snuck into the adult section,” Dailey’s sister, Evelyn Bettin of Leon, Iowa, told me.

Then came the day when “she threw a book down in disgust and said, ‘I can write a better one than that,’ ” Bettin said. Janet’s husband, Bill Dailey, dared her to do it. They sold the construction business, bought an RV and took to the road. While Bill did the research, Janet wrote a book set in each of the 50 states, which became known as her Americana series and which earned her a spot in the Guinness Book of World Records as the first author to do so.

In 1978, they settled in Branson, where Janet Dailey’s mother and step-father were living. Bill’s son, Jim Dailey, said his father worked in land development and music promotion and owned a nightclub, The Wildwood Flower.

But in 1997 it all fell apart when Nora Roberts sued Dailey for copyright infringement and won an undisclosed out-of-court settlement that she donated to literacy groups.

Dailey blamed her transgression on the stress of her husband’s illness (he died in 2005). There were many in the romance field who could not forgive her, but there are others who believe her husband played a Svengali-like role in her career and created too much pressure on her to produce.

The couple sold their Southern plantation-styled mansion overlooking Lake Taneycomo and downsized while Janet took care of her ailing stepfather. Her stepson and stepdaughter lived nearby and she enjoyed her grandchildren and even great-grandchildren. “She tried to live her life to the fullest,” her stepdaughter Linda Scheibe said. “She was always up for an adventure.”

In 2001, Kensington Publishing offered Dailey a seven-figure, four-book deal; this past October, her “Merry Christmas, Cowboy” made it to number 13 on Publishers Weekly Adult Mass Market list.

But Dailey’s career never truly recovered from the revelation that she had plagiarized another author’s work, not just once but over the course of several years.

Among writers, “plagiarism is treason,” Wendell said. “There’s no bigger betrayal.”

Author Susan Elizabeth Phillips wrote on Facebook that Janet Dailey has “left a complicated legacy … for now, I choose to celebrate the early years of her career when she changed the face of American romance publishing.”

Dreyer summed it up well: “Like every human on Earth, she was more complex than the headlines.”