Complex sentence: Nevada State Prison, which was the only state penitentiary for many decades, underwent expansion in the early 1960s in the form of a second facility in Carson City that would become known as Northern Nevada correctional Center.
Split into simpler sentences: Nevada State Prison, also in Carson City, which was the only state penitentiary for many decades, underwent expansion in the early 1960s. The result was a second facility in Carson City that would become known as Northern Nevada Correctional Center.