In the 19th century, a vast portion of the Southwest United States was under Mexican rule. This included California, which was a province called Alta California.

In 1835, a revolt started in Texas, also a Mexican province. Americans such as Stephen F. Austin and Sam Houston led the rebellion and created an independent nation known as the Republic of Texas.

Texas stayed independent for almost a decade until it became the 28th U.S. state in 1845. That triggered the Mexican–American War.

The U.S. president at the time, James K. Polk, sent John C. Frémont on an expedition to the Sierra Nevada in Eastern California. In addition, Polk allegedly secretly instructed Frémont to further expand U.S. control of California by making use of any unrest that could occur.

“There were already a lot of Americans who were starting to settle in Mexico-California and they liked the idea of California becoming part of the United States. They thought the Mexicans were behind the times economically,” Jarrell Jackman, a historian and former executive director of the Santa Barbara Trust for Historic Preservation, told The Epoch Times.

In California, Frémont encouraged local American settlers to rebel against Mexico.

On June 14, 1846, about 30 Americans including William Ide and Ezekiel Merritt trotted into Sonoma, a town in Northern California. They were prepared to take over the town by force, but the local general immediately surrendered.

Merritt and Ide created a flag with a bear on it and declared California its own nation called the California Republic. The event is known as the Bear Flag Revolt.

The new nation existed for 25 days.

“The Bear Flag Revolt became symbolic of the new America that was going to take over California for the United States,” Jackman said.

Meanwhile, John Sloat, commander of the U.S. Navy’s Pacific fleet, had similarly been ordered to attack in the event that war was declared. Sloat heard of riots and headed to Monterey, where the Navy took control on July 7, 1846, and raised the U.S. flag.

The Bear Flag was replaced with the U.S. flag on July 9, 1846, ending the Bear Flag Revolt.

Frémont worked together with Sloat and Commodore Robert Stockton to expand U.S. territory. Eventually, they took over San Diego, Los Angeles, Santa Barbara, and San Francisco.

The United States officially annexed California in 1848, and it became the 31st state in 1850. It officially adopted an altered version of the bear flag as its state flag in 1911.

The bear chosen to represent the state is the California grizzly bear, as a symbol of strength and independence. The California grizzly was a subspecies of the brown bear and has been extinct since the 1920s. It became the state animal in 1953.