From the Boise State University web page:
Bronco Stadium is the home of Boise State University football and the Famous Idaho Potato Bowl (formerly the Humanitarian Bowl), held each December.
The summer of 2012 marked the most recent expansion of the stadium, adding 3,500 permanent seating in the North and South endzones, bringing the current capacity to 36,387.
In 2009 temporary, mobile seating was added in the North and South endzones, increasing capacity to 33,500.
In 2008 the Stueckle Sky Center was opened and the capacity of Bronco Stadium went up to 32,000. The four level facility includes loge boxes, club seating, sky suites and game/media operations for Boise State home football games. Additionally, five individual banquet style or meeting room spaces are located throughout the 131,000 square foot facility.
The stadium was expanded to 30,000 seats prior to the start of the 1997 football season. The two-year expansion project raised the seating total from 22,600 to 30,000 seats. Included in the $10 million project is the additional seating in the southwest and southeast corners, construction of the Allen Noble Hall of fame gallery and completion of the Larry and Marianne Williams Plaza.
Originally constructed with 14,500 seats at a cost of $2.2 million in 1970, Bronco Stadium has undergone two expansions since then. In 1974, the east side upper deck was added, increasing the seating capacity to 20,000. Portable end zone seating had the capacity of Bronco Stadium at 22,600 through the 1996 season. At that point, the most recent expansion took place, raising the current capacity to 30,000. With the original cost of Bronco Stadium, and the two subsequent expansions, the total cost of Bronco Stadium is estimated over $13.54 million.
Bronco Stadium is also home to the only blue Astro Turf in the World. The current turf is the new "Astro Play" which was installed during the summer of 2002. It's also the third blue field at the stadium. Boise State established a first in 1986 by installing the first blue Astro Turf field. The second blue Astro Turf was installed in 1995. Other schools have special color projects for the end zone area, but Boise State is the first to have the entire field produced in a special color. There have been two previous green Astro Turf fields installed prior to 1986. The first was during the original construction of the current stadium in 1970, with the second installed prior to the 1978 season.