Decked out in red, white, and royal blue and dancing to patriotic songs, tens of thousands of parade-goers lined Fifth Avenue yesterday for the 50th annual Puerto Rican Day parade. Some of the attendees fashioned shirts and skirts out of the country’s flag, while others showed their pride with noisemakers and face paint.

“I’m just so happy,” a resident of Spanish Harlem, Zoraida Carrion, said. “It’s the only day we can really celebrate who we are.” On Saturday night, Ms. Carrion, 14, drew Puerto Rican flags and a map on a T-shirt and her jeans to prepare for the parade.

Marchers made their way up Fifth Avenue to 86th Street from 44th Street, chanting, “Yo soy Boricua!” (“I am Puerto Rican!”) to the crowds watching from the sidewalk, packed 50 deep at some spots.

Mayor Bloomberg, Governor Spitzer, the governor of Puerto Rico, Anibal Acevedo-Villa, and pop star Ricky Martin cut a ceremonial ribbon at the start of the parade, the largest ethnic parade in the country. Mr. Martin was named the parade’s king this year, the first time the honor has been bestowed.

Public officials, including Rep. José E. Serrano, a Democrat of the Bronx, waved to the crowd and shook hands with supporters as they walked along the 42-block route.

Mr. Serrano, who was with his son, state Senator José M. Serrano, said he was proud to participate in the parade with his fellow Puerto Ricans.

“This is the one day during the year when we celebrate that Puerto Rico has made New York a bilingual town,” Mr. Serrano said.

Puerto Ricans are the largest Hispanic group in New York, with 789,000 of the city’s 2.1 million Hispanics, according to city figures.

Eighty people were arrested at the parade this year, up from nearly 70 last year.