How many employees make up an HR department?

I’m working my BA right now and I’m really interested in working in HR once I graduate.

I work at a bank now and we have quite a few people in our HR department (probably around 10). However, my boyfriend works at a factory and there’s only one HR employee that runs the entire department. So, in general, how many people work in a company’s HR department?

I read on bls.gov that the job outlook for HR assistants is supposed to slowly decrease through 2018 but HR manager positions are quickly increasing through 2018. I’m graduating in 2013, so I’m wondering exactly how difficult it will be the find an entry level job in HR so I can work my way up before these jobs disappear.

The city I’ll be looking for work in is Charlotte, NC if that helps.

Also, if I get an internship in the HR department of a company while I’m in school and then can’t find work in HR after I graduate, is that a wasted internship or could it help me with other jobs as well?

What other jobs like HR could I look into as a back-up plan with a BA in Psychology and a minor in Business Administration?