[5] In 1885, it came into the possession of the Corte Madera Rancho del Presidio, one of the largest ranches in Marin County at the time.

[6] Its proprietors were sued by the United States in 1891, alleging that they had procured the island (among some 4,000 acres (1,600 ha) of land in the area) through a "false and fraudulent plot, alleged to have been made by field notes of an actual survey".

[6] In 1908, construction of railroad track for the Green Brae–Corte Madera cutoff involved workers cutting through the southeastern end of the island;[7] by 1925, it had become part of the Keever estate.

[9] Of four tracts, one was approved by the city to be annexed by ordinance—the "Fifer-Moore addition", located on Richardson Island.

[10] Larkspur had previously attempted to block annexation of the island by "cutting it off" from Corte Madera.