Never been to these, yet.
For southern and central California there is CalStar at Lake San Antonio. They throw end-of-season and Spring Binge events, both, three nights. Free, except $45 per vehicle to get in the park. Load up 4 or 5 participants in an RV and save a bundle. Here's the link:
http://calstar.observers.org/
Then there is Grand Canyon party, really big one. Here's the link for 2025:
https://www.nps.gov/...-star-party.htm
There is also Death Valley Star Party.
https://lvastronomy.org/DVSP.html
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A couple of unorganized smaller ones that can attract large crowds I go to all the time. You will find others here weekends around New Moon. I have seen huge crowds at both. Probably be better now with the economy improving. People from Los Angeles, Santa Clarita, Antelope Valley and Bakersfield areas show up here, so it can get quite big.
Mt Pinos, every new moon from about May to September. Usually sky conditions are very good. Back in the '90s it was "standing room only", there were even people set up at the three last pull-outs before the Nordic Base parking area. Negligible cell service, but it's spotty. Vault toilets are 600 ft to the hike-in Chula Vista Campground, bring paper in case. Here is the Google Maps location:
https://www.google.c...KXMDSoASAFQAw==
Chuchupate (choo-choo-puhtay or, choo-choo-potty) Frazier Mtn Trailhead parking lot. No camping allowed but the rangers make complete exception for amateurs. Not as good as Mt Pinos, but 10* warmer. It's also fairly secure due to the ranger station down the road. In-season, typically both ends of the lot can get nearly full with "dark encouraged" in the Northwest end for imaging. Vault toilets on site, bring paper in case. If it's hosting an ATV event, head to Pinos. As for cell coverage, AT&T, etc gets in here, there's a tower in Lake of the Woods. Here is the Google Maps location:
https://www.google.c...KXMDSoASAFQAw==
Clear skies...