The 6-5, 280-pound lineman, who was a two-time All-Northern California lineman, signed a letter of intent with USC on Wednesday and will enroll in January.
"I got offered last week and I just kind of thought about it and decided that USC is really good academically, I like the coaches and it is a great football opportunity," Galten said. "I decided today to sign."
Galten grew up a fan of the Trojans and said his entire family was thrilled with his decision to commit to USC.
"My stepdad and his brother and my grandfather all went to USC so there is a lot of family tradition," he said. "I have always been a USC fan.
"It's like a dream come true, for not just me, but my whole family."
The big offensive lineman played guard at San Mateo but has the ability to play either guard or tackle when he arrives in Los Angeles.
"I told them I would play either. I am just trying to be as versatile as possible," he said. "They asked me at CSM to pull a lot so I just see myself as a bit more athletic them other linemen."
San Mateo assistant coach Tim Tulloch added: "He played guard for us, but he's got enough athleticism to play on the edge at tackle. He's a really good player and someone who USC will be really happy they got down the road."
He was recruited by USC quarterbacks coach Clay Helton, and said his relationship with Helton was a big factor in his decision.
"He just kind of guided me through the whole process," Galten said. "He wanted me to go to USC, but he was always really open about getting the best opportunity for me, and it just happened to be USC."
Galten will have three years to play two for the Trojans.
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