Author of New York Times bestselling novel Bridges of Madison County, Robert James Waller, has passed away in Texas. He was 77.

The news was reported by his literary agent, Lucy Childs of Aaron M. Priest Literary Agency, but the cause of death not yet known. Childs stated that Waller passed away either late Thursday or early Friday and had been “ill.”

Bridges of Madison County, a 1992 bestselling novel was famously penned by Waller in 11 days and turned into a movie starring Clint Eastwood and Meryl Streep in 1995. It illustrates the four-day romance that unfolds between impassioned National Geographic photographer Robert Kincaid (Eastwood) and bookish and shy Italian-born Francesca Johnson (Streep).

Waller’s sappy, romantic novel excelled to the No. 1 spot on the New York Times bestsellers list and remained there for three years. After the movie directed by Eastwood was made, it grossed $182 million worldwide.

Waller also wrote the novels, Slow Waltz in Cedar Bend, Border Music and Puerto Vallarta Squeeze, none of which surmounted to the success of his previous work Bridges of Madison County, which sold 12 million copies worldwide in 35 languages and even ignited a cult following in which tourists visit Madison County, Iowa, to wed right there on those once obscure bridges. Tourists reportedly arrive by dozens to visit this tiny little town, boasting a population of 4,200, to purchase novelty mugs, T-shirts, postcards and perfumes with Bridges memorabilia. The success of his novel turned Waller into a multimillionaire.