In the Bay Area, one of the biggest celebrations is in the City of Dublin.
On Saturday night, a 200-drone light show marked Dublin's 40th anniversary in celebrating the holiday.
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There was lots of traffic getting into Dublin. But event organizers say the southbound closure of I-680 from the I-580 interchange to Sunol didn't seem to have much of an impact.
Caltrans says all entrances to Dublin from I-680 and I-580 would be open all weekend, including for Sunday's iconic Dublin St. Patrick's Day parade.
Although the holiday is officially Sunday, there was plenty of Irish cheer in Downtown San Francisco Saturday.
The city celebrated its 173rd annual Saint Patrick's Day Parade and celebration.
MORE: Remembering how Irish immigrants helped shape SF as Saint Patrick's Day
Crowds of people wearing green and shamrocks filled the streets as the parade went from Market and 2nd Streets all the way to Civic Center Plaza.
And there was plenty of green to go around.
The theme of the day was unity. Everyone in the city came together with just an extra sprinkling of luck.