On a frigid night in January, the rollicking sounds of drums, bass, accordion, guitar, and washboard poured from the Hungarian House on East 82nd Street. Inside, Upper East Siders and people from the metropolitan area and beyond filled the auditorium, dancing to syncopated music that drew them in from the streets. Many of them probably hadn’t ever heard of zydeco or Cajun music before, but that’s the way it usually is with the Louisiana-based music and dance parties that have been attracting attention in New York and around the country. The celebration begins again this Monday evening with the Grammy Award-winning zydeco band BeauSoleil at Connolly’s restaurant in Midtown.

Long before Hurricane Katrina forced thousands of people from New Orleans and the surrounding area to make their homes elsewhere in the United States, zydeco and Cajun music of Louisiana had started winning fans outside the region. But since the storm, the two rural music traditions have gained an even wider audience. As Louisiana’s displaced citizens and musicians work to keep their culture alive wherever they travel, New York, along with Baltimore, San Francisco, Washington, D.C., Houston, Philadelphia, and many other smaller cities, is reaping the musical rewards.

A New Yorker who established a company Let’s Zydeco in 1993, Laura Selikson hardly sees a month goes by when she’s not planning a zydeco or Cajun party in Manhattan. Despite the entrance fee and location — at clubs like Tramps, La Belle Époque, and Satalla — most zydeco parties feel like family affairs once held in roadhouses in the bayous. In July, Ms. Selikson featured the popular Geno Delafose and the French Rockin’ Boogie at Connolly’s restaurant and bar on West 45th Street. On a recent Sunday, Let’s Zydeco brought Steve Riley and the Mamou Playboys, one of the country’s best Cajun bands, to the same restaurant. Mr. Riley says he has had more bookings since Hurricane Katrina than ever before in his 20-year career.

Though Ms. Selikson’s dance parties have always attracted boisterous crowds, she says she has seen an increasing number of newcomers joining the faithful. “There’s nothing like seeing the reaction of people who have never heard or danced to this music,” she said. “It’s like they’ve discovered a whole wonderful and exotic new world.”

Actually, though they have French roots, Cajun and zydeco are indigenous to America. When the French-speaking Arcadians, later called Cajuns, left Nova Scotia for Louisiana in the 1750s after being expelled by the British, they brought with them music that combined their French heritage with that of the American Indians and British settlers with whom they had recently lived.

At the beginning of the 20th century, Creoles, the African-American descendants of slaves from the French West Indies, developed music in southwest Louisiana, borrowing from the sounds of American Indians and people from the Caribbean. As both groups settled into their new, shared home, they began picking up some of the same influences.

These days, both styles are still often sung in French, but they are distinguishable by their instrumental characteristics. The Cajun sound derives from the fiddle, accordion, guitar, and triangle, whereas zydeco is characterized by chugging rhythms, the use of the washboard, or frottoir, and the strong influence of R&B, Caribbean rhythms, and, increasingly, those of rock, reggae, and hip-hop.

One of zydeco’s first stars, Clifton Chenier, who came to popularity in the 1950s, invented the term for the music from a corruption of the French word for beans, “haricots.” Chenier had used the word in one of his hits, “Les Haricots Sont Pas Sales” (“The Snap Beans Aren’t Salty”), a reference to the singer being too poor to afford salt pork to season his beans.

At the zydeco party in July, few of the people dancing to Mr. Delafose’s vigorous band likely knew the music’s history. But no matter. What they did know was that it made them want to dance. To aid them, Ms. Selikson or another expert teaches the basic 8 beat step before every event.The dance move can be embellished with kicks, toe and heel taps, brushes, and other steps known as “eata-beat.” At most parties, experienced dancers help the novices.

A New Yorker who gives workshops in international folk dance, Fredda Seidenbaum has taught zydeco and Cajun dancing privately and at Columbia University and the New School. “A crucial test of a good zydeco or Cajun musician,” she said, “is how well he knows how to dance. They have to know how to support the dancers. They love seeing people dance well. It’s a real exchange.”

For Louisianans, the new popularity of Cajun and zydeco music and dance is a welcome trend. Nesbit Parker, who lives in New Orleans, dropped in to the recent party at Connolly’s during a trip to New York to celebrate her birthday. “This music is so fundamental to our region,” she said. “To see it enjoyed by people from so many places is like you yourself and your family are being welcomed. There’s isn’t music with more soul and honesty.”

A painter who moved from New Orleans to New York after Katrina, Vidho Lorville echoed her words. “When I dance to this music,” he said, “I am home again.”

Let’s Zydeco presents BeauSoleil at Connolly’s (121 W. 45th St., between Sixth Avenue and Broadway). For more information, call 212-685-7597 or visit www.letszydeco.com.