The school, located 26 miles north of the State Capitol, was, for many years, in a rural agricultural community with one non-agricultural industry, Round Rock White Lime Company, which quarried and milled and processed lime.  In 1934 there were 16 members of the graduating class.

There were few changes in the community or the school until the 1960s.  In 1964, the enrollment of RRHS was 324, but growth had begun.  Hopewell Negro School closed in 1966 and students were integrated into one high school without incident.  During 1974, enrollment at RRHS grew from 855 to 1,000.  By 1984 there were two high schools in the district, with a total of 4,443 students, 2,508 of them at Round Rock High School. 

In 1994, there were three high schools in the district with a total enrollment of 6,234, and of those, 2,641 were at Round Rock High School.  During the 1998-1999 school year, before the district's fourth high school was built, RRHS reached an all-time high of 3,600 students and was the largest high school in Central Texas.  In 2003-2004 school year, RRISD has four high schools with a high school enrollment of 9,912 students, 1,954 of which are proud Dragons!