Hi, I’m just a girl who was recently accepted to a graduate school program at very well-known Southern California university for 2 years. I’m coming from Southern California as well, but I didn’t do my undergrad in Los Angeles. Thing is, I didn’t make any long lasting friendships while I was at college, so I don’t have many friends. I was hoping that attending grad school in the same area I grew up in could not only let me have job opportunities closer to home, but make new friends in the area too. I’m just worried that the other students won’t want to make new friends since most of them are already in their “cliques”. I know everyone says to get involved, but are there other things I can do to meet people? Thanks!
I don’t have a single friend from college, but I met my H in grad school.
I met my husband in grad school, also. We had two classes together and were engaged within three months. Still going after being married almost 32 years. 
Graduate school classmates often become long term friends due to shared interests & similar career/profession.
Live in the graduate dorm if there is one. You will meet people from lots of different departments, not just your own program. I met my husband there, as well as several other friends that we still are close with more than thirty years later.
I talk to about as my of my undergraduate friends still as I do my high school friends, which is to say, very few. Meanwhile, I am meeting up with two other friends from graduate school who all live in different parts of the country for a summer vacation this year.
You’ll be fine.
Most of my close friends that I still talk to and socialize with are from after college. I’ve got three really close friends I met in graduate school around 2011 and we’re still friends - talk regularly and take trips together, even though we’re not in the same area of the country. I also have a small circle of local friends that have lifelong quality (after you get to a certain age, you can tell pretty early IMO) that I met at work or through other networks.
Making lifelong friends doesn’t end in college. And people can often become less cliquey after college, too - meaning that just because people have a group of friends doesn’t mean they aren’t open to making new ones.