What does "campus" mean though?
Especially at the smaller end.
Are some these campuses just a single building? They don't all have their own infrastructure and administration do they?
They are campuses. Take the Shenango Campus for 321 students and has 10 buildings. The Greater Allegheny Campus is on 59 acres for 396 students. Some are just one or two buildings but many of them are full blown campuses. They all operate under a bigger umbrella but I am sure there is a lot of duplication of services.
The Shenango campus consists of ten educational and support buildings including:
Sharon Hall (built 1928): The primary classroom and office building on campus houses administration, faculty offices, computer labs, classroom space, and the Great Hall student center.
Lecture Hall (built 1904): Includes campus admissions and financial aid offices, classroom space, and faculty offices. A glass atrium connecting Sharon and Lecture halls was constructed in 2006.
Science Building (built 1968): Includes faculty offices and science classrooms. This building is now considered a section of the Forker Laboratory building as part of a $8.5 million renovation that was completed in 2021.
Forker Laboratory (built 1972): Science labs, classroom space, and the Forum, a large classroom used for lectures and events is located here. The Physical Therapy Assistant program is housed on the second floor. An $8.5 million renovation, which included a new HVAC system, science equipment upgrades, and the addition of Engineering and Physics equipment, was completed in 2021.
Chadderton Laboratory: The former headquarters of the local television cable company, this building was renovated in 2013 and houses the Occupational Therapy Assistant program, including office, classroom, and laboratory spaces.
McDowell Hall: Houses the campus bookstore, Human Development and Family Studies, Administration of Justice, and Administration of Justice Crime Lab.
Lartz Memorial Library: Originally housing a commercial laundry, and then a local steelworkers union hall, the Library was renovated in 1996 and houses the campus library collections, study areas, a classroom, and the Media Commons.
B&B Building: Another former office building that is currently used for storage. Prior to storage, this building was home to the Physical Therapy Assistant program and Ag Extension office.
Penn State Theatre (Auditorium) (built 1928): The former Auditorium of the Sharon Central School District, now used for large gatherings including commencement, concerts, and the Penn State Lecture Series. A multi-phase renovation project began in 2008.
Maintenance Building: Houses campus maintenance department and services.