Last year, 15,000 people descended on Hippie Hill, which is now known as Robin Williams Meadow.
VIDEO: Bigger crowds expected at SF's 4/20 celebration now that cannabis is legal
The gates opened at 9:30 a.m. Friday, 30 minutes late because staff members were still checking security around the fenced in area.
Organizers have 60 security officers at the event this year as opposed to 40 last year.
MAP: Where is weed legal?
There is also more food, security and bathrooms than last year. Organizers tripled the amount of food by having 20 vendors instead of six.
ABC7 News met people at the park who said they are there to celebrate the fact that recreational pot is now legal. "We traveled 150 miles to be part of this event. It is the first legalization of marijuana. So, we thought we were too young for Woodstock and we have had this as a bucket list," Tammy Delong said.
Organizers have even stationed some bathrooms on Haight Street as they expect the crowd to spill out over there and to be in and out on this beautiful Friday.
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City officials say it neither condones nor sanctions this event, but works with a private sponsor to pay for the security and fencing it takes for this day.
At 4:20 p.m., thousands will converge on Golden Gate Park to light up.
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This year’s 4/20 has a different feel to it... legalized! pic.twitter.com/5uBEtYbSn4— Amy Hollyfield (@amyhollyfield) April 20, 2018
Gates are open at Golden Gate Park for 4/20. Record crowds expected. pic.twitter.com/aWB6j4jZU3— Amy Hollyfield (@amyhollyfield) April 20, 2018
Crowd waiting to get in to Golden Gate Park for 4/20 celebrations. Supposed to open at 9:00- still checking security around the park. pic.twitter.com/EZD5D3KQ99— Amy Hollyfield (@amyhollyfield) April 20, 2018