Texas Academy of Mathematics and Science is one the best and biggest Early Entrance program in USA. Every year.
http://www.tams.unt.edu/
TAMS has been a critically-acclaimed program since its inception in 1987. The students represent the entire range of Texas cultures and regions, and are distinguished by their love of learning. Almost half are females who achieve at the highest levels, right along with their male counterparts.

The TAMS environment is decidedly safe, and students enjoy an active social life with unsurpassed opportunities for learning, research, and recognition.

About 200 students are admitted each year. As TAMSters, they take university classes taught by degreed professors. They also may choose to do supervised research, which can lead to national awards and exclusive scholarships.

For recreation, they have access to a $25 million Student Recreation Center, featuring weight-training and fitness equipment; 45-foot climbing wall; jogging track; indoor and outdoor multipurpose courts; 25-yard, eight-lap pool; a 5,510-square foot leisure pool with a flowing water channel, swirling vortex, water fountains, spray tunnel, water curtains, and underwater seating; and a 445 square-foot whirlpool spa.

Also available nearby are exercise rooms, lighted tennis courts, all-weather track, game room, movie theater, and food courts. After two years, TAMSters will have earned at least 57 college credits. They may then either continue their education at UNT, or transfer to other universities in state or out, usually at advanced standing.