Recently, Google has emphasized that when hiring, it’s putting less weight on where a graduate went to school. But for those who want to end up in Silicon Valley, going to school in California might be a boost.

Using LinkedIn data, we took a look at the top 20 feeder schools where current employees from Google, Facebook, Apple, and Twitter attended. (The data are imperfect because the number of profiles on LinkedIn don’t match the number of employees each company lists on its corporate filings. Not every employee lists education, and employment and university affiliation aren’t verified by LinkedIn.) Pedigree doesn’t seem to hurt either—about 15% of Google employees came from the top 10 highest-ranked engineering schools in America. But across the board, geography matters.

“There’s definitely a high concentration of graduates from those schools that stay in the Bay Area,” Scott Purcell, a Silicon Valley-based technology recruiter at Jobspring Partners told Quartz. “In particular, the really top brand name companies like Google, Facebook, Twitter, and Square have a built in pipeline from all of those universities. Their top talent already comes from there, so they have all of the connections.”

Here’s how employees’ alma maters break down at Google, Facebook, Apple, and Twitter:

Google

At Google, Stanford leads the pack, followed by UC Berkeley; 12.53% of profiles come from California schools, which make up nine of the 20 biggest alumni populations. Google employs 47,756 people, and 43,282 people cite it as their current employer on LinkedIn.

Facebook

Stanford and Berkeley lead at Facebook as well, with an even greater portion of the alumni population coming from the those schools than at Google. More than 16% of the employees with profiles on LinkedIn listed attending a school in California. As of December 31st, the company had 6,337 employees. 5,777 people say they work at Facebook on LinkedIn.

Apple

At Apple, which has nearly twice as many employees as Google, the concentration from each school is lower. Only one of the six biggest alumni populations is from a school outside of California. Overall, 6.5% of profiles were from in state. Apple employs 80,300 full-time employees, and 4,100 full time temporary employees and contractors; 42,800 of its employees work in the retail part of the business; 75,920 people Apple as their current employer on LinkedIn.

Apple’s large retail staff works in stores throughout the United States and the world, which could help explain the lower concentration of California graduates.

Twitter

Twitter, the youngest company of the four, has the highest overall concentration of California alumni, with big populations from Stanford and Berkeley, as well as other California state schools. More students, 18%, come from California schools than the rest of the top 20 feeders combined.

Twitter has not filed a 10K yet, but had “over 2,300 employees” when it filed for its IPO late last year, not far from the 2,432 who list it on LinkedIn.