Union Oil Company of California, dba

Doing business as

The phrase "doing business as" is a legal term used in the United States, meaning that the trade name, or fictitious business name, under which the business or operation is conducted and presented to the world is not the legal name of the legal person who actually own it and are responsible for it...

 Unocal (ˈjuːnɵkæl) is a defunct company that was a major petroleum explorer and marketer in the late 19th century, through the 20th century, and into the early 21st century. It was headquartered in El Segundo

El Segundo, California

El Segundo is a city in Los Angeles County, California, United States. Located on the Santa Monica Bay, it was incorporated on January 18, 1917, and is one of the Beach Cities of Los Angeles County and part of the South Bay Cities Council of Governments...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, United States.

On August 10, 2005, Unocal merged with Chevron Corporation

Chevron Corporation

Chevron Corporation is an American multinational energy corporation headquartered in San Ramon, California, United States and active in more than 180 countries. It is engaged in every aspect of the oil, gas, and geothermal energy industries, including exploration and production; refining,...

 and became a wholly owned subsidiary

Subsidiary

A subsidiary company, subsidiary, or daughter company is a company that is completely or partly owned and wholly controlled by another company that owns more than half of the subsidiary's stock. The subsidiary can be a company, corporation, or limited liability company. In some cases it is a...

. Unocal has now ceased operations as an independent company, but continues to conduct many operations as Union Oil Company of California, a Chevron company.
The company was founded on October 17, 1890, when it was incorporated in Santa Paula, California

Santa Paula, California

Santa Paula is a city within Ventura County, California, United States. The population was 29,321 at the 2010 census, up from 28,598 at the 2000 census...

, as the Union Oil Company of California.