Shortly before Leidesdorff's death, vast amounts of gold were officially reported on his Rancho Rio De los Americanos.

International Leidesdorff bicentennial celebrations began on October 22, 2011, on his native isle of Saint Croix, U.S. Virgin Islands.

[2] As his parents were not legally married, Leidesdorff was considered illegitimate until July 18th, 1837, when a Crucian court formally recognized his birth, allowing him to inherit his father's property.

Leidesdorff, Jr.'s mother Anna Marie Sparks, was described in one account as a Carib Indian woman; she was believed also to have had African and European ancestry.

[4] Other sources said the mother Marie Anne Spark (as she was also known) was a mixed-race woman of African and Spanish heritage, thought to have been born in Cuba.

[5] Other sources document tens of thousands of Caribs, most of mixed heritage, living in the Windwards and Trinidad at the time of Leidesdorff's birth.

[6] According to Sue Bailey Thurman, "With the name of William Alexander Leidesdorff, we begin the documentary history of pioneers of Negro origin in California.

[7] In 1837 Leidesdorff Sr. officially "adopted" all four of his own children from Anne Marie Sparks to give them legal standing by Danish Law.

William Alexander Leidesdorff, Jr. was thought the last black ship captain in Louisiana after strict enforcement of the Negro Seamen Acts began at the Port of New Orleans.

[7] His route was via Panama, St. Croix, Brazil, Chile, the Sandwich Islands (Hawaii), Sitka (Alaska), and on to California following the Pacific Ocean currents.

[8] He launched the first steamboat to operate on San Francisco Bay and the Sacramento River; it was 37 feet (11 m) long and purchased in Alaska.

In 1844 Leidesdorff obtained a vast land grant through favor from the Mexican government for 35,521 acres (143.75 km2) on the south bank of the American River, near today's Californian City of Sacramento.He named the property Rancho Rio de los Americanos.

In March 1848, the California Star reported the total non-Native population of San Francisco as only 812: 575 males, 177 females and 60 children.

The public discovery of gold in the American River valley and upon his extensive land holdings increased the actual value of his estate dramatically.

The dispute was brought to the courts, where legal entanglements over the conflicts of Mexican, American and Danish laws kept it for over ten years.

Leidesdorff's St. Croix relatives, mother and siblings, challenged title through Danish officials because of Folsom's false evaluation of the estate.

In 1854, Governor Bigler, recommended the escheat of the estate, then worth a million and a half, to the state legislature, and suggested that proceedings be commenced for its recovery from Folsom.

[15] The courts refused to admit the title of the West Indian mixed-race relatives because there may have been "other heirs, who had never conveyed away their rights in the estate", from Europe.