BROWNSVILLE, Texas — One of the nation's poorest urban school districts won a coveted $1 million prize today for doing so well in guiding its nearly 50,000 students toward academic achievement.

The Broad Prize for Urban Education is the nation's largest award of its kind and will be divided among the district's graduating seniors for college scholarships.

"Brownsville is the best kept secret in America," said billionaire Eli Broad, founder of the Eli and Edythe Broad Foundation, announcing the decision in New York. He praised the Brownsville Independent School district for "smartly focusing all resources on directly supporting students and teachers."

Brownsville, in the southernmost tip of Texas, beat out other finalists Aldine, a district in Houston; Broward County, Fla.; Miami-Dade County, Fla.; and Long Beach, Calif. Each of those finalist districts will receive $250,000 for college scholarships.

"This is considered the Nobel Prize in education," an elated Hector Gonzales, the district's superintendent, said by phone at the award presentation in New York.

Brownsville's student population is overwhelmingly Hispanic, and 94 percent qualify for a free or low-cost lunch, a common measure of poverty. The district impressed the foundation's judges by outperforming other Texas districts with similar income levels in reading and math at all grade levels in 2007.

Some 2,000 new arrivals from Mexico join the district's classrooms every year, and teachers emphasize mastery of English in their classes. Alan Ponce, 18, was one of those new arrivals. Born in Monterrey, Mexico, he moved to Brownsville in 2002 and is now a senior at Gladys Porter High School.

He said that when he heard about the award over the loudspeaker Tuesday morning, "I heard two words: million dollars and scholarships," he said.

"It's a huge relief because my parents make very little money," said Ponce, who hopes to study physics and astronomy in college. "It makes me think I can go to any Ivy League school I want to."

Broad co-founded homebuilding pioneer Kaufman and Broad Inc. and launched financial services giant SunAmerica Inc.