OCTA's predecessor agency, the Orange County Transit District, was created in August 1972 by a referendum of county voters.
It originally started as Santa Ana Transit, a small transit agency with five bus routes operating in Orange County.
Santa Ana Transit later merged with other, smaller agencies throughout the county, eventually leading to the formation of OCTD.
The routing system was formed over the course of about 15 years and was held in place until the merge to OCTA.

In 1991, OCTA was created under state law, combining the seven separate Orange County agencies that managed transportation planning:
Orange County Transportation Commission
Orange County Transit District
Consolidated Transportation Services Agency
Orange County Local Transportation Authority
Orange County Service Authority for Freeway Emergencies
Orange County Congestion Management Agency
Orange County Service Authority for Abandoned Vehicles
Park-and-ride facilities, public transportation and other transportation related administrative offices merged into one organization.
OCTA administers funds from Measure M (also known as OC Go), the half-cent transportation sales tax.
Measure M was originally passed in 1990 and renewed in 2006.
It has paid for the expansion on most freeways within Orange County, street improvements and repairs, traffic signal synchronization, and increased Metrolink service.

In 1995, OCTA suffered tremendously during the Orange County bankruptcy and never fully recovered.
The agency lost $202 million in revenue over 17 years due to the bankruptcy.
As a result, bus service was reduced.

In October 2015, OCTA rebranded its bus services as "OC Bus" and launched the OC Bus 360° plan, which aims to consolidate routes into more frequent service and increase ridership.
OCTA also plans to replace 40% of its bus fleet with compressed natural gas-powered vehicles.
The change was approved by the OCTA board on February 22, 2016.
OCTA's predecessor agency, the Orange County Transit District, was created in August 1972 by a referendum of county voters. It originally started as Santa Ana Transit, a small transit agency with five bus routes operating in Orange County. Santa Ana Transit later merged with other, smaller agencies throughout the county, eventually leading to the formation of OCTD. The routing system was formed over the course of about 15 years and was held in place until the merge to OCTA.
In 1991, OCTA was created under state law, combining the seven separate Orange County agencies that managed transportation planning:
Orange County Transportation Commission
Orange County Transit District
Consolidated Transportation Services Agency
Orange County Local Transportation Authority
Orange County Service Authority for Freeway Emergencies
Orange County Congestion Management Agency
Orange County Service Authority for Abandoned Vehicles
Park-and-ride facilities, public transportation and other transportation related administrative offices merged into one organization. OCTA administers funds from Measure M (also known as OC Go), the half-cent transportation sales tax. Measure M was originally passed in 1990 and renewed in 2006. It has paid for the expansion on most freeways within Orange County, street improvements and repairs, traffic signal synchronization, and increased Metrolink service.
In 1995, OCTA suffered tremendously during the Orange County bankruptcy and never fully recovered. The agency lost $202 million in revenue over 17 years due to the bankruptcy. As a result, bus service was reduced.
In October 2015, OCTA rebranded its bus services as "OC Bus" and launched the OC Bus 360° plan, which aims to consolidate routes into more frequent service and increase ridership. OCTA also plans to replace 40% of its bus fleet with compressed natural gas-powered vehicles. The change was approved by the OCTA board on February 22, 2016.
Orange County Transportation Authority