Cummings, 25, is a Panama international who last played for Costa Rican outfit Alajuelense on loan, where he went on to make 23 appearances, scoring one goal.
"Harold is an talented young player and we’re excited to add him to our roster," Earthquakes technical director Chris Leitch said in a club-issued statement. "To have nearly 50 international appearances before his 25th birthday ensures we’re getting a player with a rare combination of youthfulness and experience."
He joins a San Jose team during a time when the club is rebuilding its back line; there are only five defenders currently listed on the Earthquakes' roster, and six if versatile right winger Cordell Cato continues to play at right full-back.
For his part, Earthquakes head coach Dominic Kinnear is excited to implement Cummings into his team plans ahead of the start of the 2017 campaign.
"I have seen a lot of Harold during his time with Panama," Kinnear said in the club's statement. "He's a very aggressive, intimidating young center back, who will add a good amount of strength to our back line."
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