During the 1840s, prior to the gold rush, William Leidesdorff engaged in trade and real estate. He built San Francisco’s first hotel and was the city’s first treasurer.

Leidesdorff was born in St. Croix in the Danish Virgin Island. He was the son of a Danish planter and African woman. As he became of age, he was sent to New Orleans to work in the office of his two brothers in the cotton business. After the death of both his brothers, Leidesdorff inherited the business and became quite wealthy. He soon left New Orleans and relocated to California, allegedly due to an unhappy romantic relationship.

At the time Leidesdorff arrived in California, the state was in the middle of a three-way power struggle between Mexico, who owned it, and the United States and Great Britain, who wanted it. In 1843, Leidesdorff was able to secure a land grant from Mexico for two 300-foot lots on the corner of Clay and Kearney streets. Upon his land, he built a store and home where he entertained the most influential Americans of that era.

Because of his standing in the community, Leidesdorff was soon appointed American Consul in California. Leidesdorff focused on the land grants from Mexico. He became a naturalized Mexican citizen in 1844 and quickly acquired 35,000 acres of ranch land on the bank of the American River from the government. The strategy paid off when he was appointed American sub-consul at Yerba Buena. He later built and leased a warehouse to the U.S Government.

The power struggle for California came to an end in 1846. Leidesdorff was given a proclamation of the takeover by Captain Montgomery of the United States Marines. The marines landed and raised their flag on a pole that had been vacated by the Mexican flag which had been given to Leidesdorff.

He was also credited with building the first hotel, the first shipping warehouse, and operating the first steamboat on San Francisco Bay, as well as laying out the first horse race track in California. Leidesdorff died in 1848 at the age of 38. His estate was worth approximately $1,500,000.

source:

http://www.blackpast.org/aaw/leidesdorff-william-alexander-1810-1848