The section is north of La Canada Flintridge and is used as a route between the Antelope Valley and the San Gabriel Valley.
The highway reopened at 10:15 a.m. after nearly 17 months of complex reconstruction work and $32 million in costs.
Just after the gate opened, cars, bikers and cyclists made their way through the Angeles Crest Highway.
A section of the highway closed in January 2010 when rain in the Station Fire burn area washed away several chunks of the road.
More rain in January of this year washed away another section of the road, delaying the opening of the highway.
Businesses have been suffering because of the closure. Some restaurant owners said they've seen a 90 percent downturn in the number of patrons going through the area.
"We lost about 15 percent of business," said Mark Kim of Hill Street Cafe.
Kim said he hopes the reopening helps bring back hikers, bikers and business.
There were some residents who said they enjoyed having less traffic, but most say Angeles Crest Highway and access to the forest is a perk of living in the area.
"That's sort of like living in Santa Monica and not wanting to go to the ocean," said Josh Ault of Montrose. "If you live here, you know that that's part of it."