Large crowds are expected to celebrate 4/20 at San Francisco's Golden Gate Park on Friday.
It's an annual event held in an area called Hippie Hill. This will be the first gathering since the sales of recreational marijuana was legalized.
On Wednesday evening, a tour van that embodies the spirit of the sixties drives by Hippie Hill, promoting peace, love and freedom. But neighbors tell KTVU they're bracing for disruptions come Friday.
"People walking through the streets yelling, acting stupid. They're not quite themselves at that point, " said John Chan, a homeowner who says he's lived here for 47 years.
Neighbors say they expect a larger crowd than previous years now that the sale of recreational marijuana is legal. One woman who works nearby says her office building is closing hours early.
"They're closing the doors at 1 [1:00 p.m.], so people can't go in and out of the building unless you have a card," said Kelsee Levey as she held up her employee card key.
Residents say people who come to the event often cause inconveniences, such as leaving trash and parking illegally.
"I worry about people parking in front of my driveway and it gets quite congested in this area," said David Aaronson who lives across the street from Golden Gate Park.
"Any resident or person attending that has some kind of situation or some kind of violation can call us and we can have officers respond," said Captain Una Bailey with the San Francisco Police Department.
City leaders say concerned citizens can call 311 or a special hotline for help.
A one-mile-long chain-linked fence went up around Hippie Hill Wednesday morning and is scheduled to stay up until Saturday.
There will be food vendors and porta-potties. City officials say there will be double the number of parking control officers and more private security guards than last year.
Members of the Haight-Ashbury Merchants Association and cannabis companies say they will spend $200,000 they raised to help pay for some of the costs.
"I'm a native, born and raised here. I live in the block, four blocks away. This is my park. This is our park. We should take pride in that," said Alex Aquino with the Haight-Ashbury Merchants Association.
Some neighbors say they'll leave the area Friday. Others plan to take side streets to try to get around the congestion and avoid going out except for work.
"Get home as soon as possible so you don't have to be out on the streets when it's dark, and stuff like that, and run into unsavory types," said Chan.
Officials say city workers and neighborhood groups will be cleaning up late Friday afternoon after the festivities end, as well as the following day.
Neighbors say they'll have to wait and see how it all turns out.
To report problems, city leaders say call the hotline: (415) 242-3060 or (415) 242-3061