The city is named for Pomona, the ancient Roman goddess of fruit. For horticulturist Solomon Gates, "Pomona" was the winning entry in a contest to name the city in 1875, before anyone had ever planted a fruit tree there. The city was first settled by Ricardo Vejar and Ygnacio Palomares in the 1830s, when California and much of the now-American Southwest were part of Mexico. The first Anglo-Americans arrived in prior to 1848 when the signing of the Treaty of Guadalupe Hidalgo resulted in California becoming part of the United States. By the 1880s, the arrival of railroads and Coachella Valley water had made it the western anchor of the citrus-growing region. Pomona was officially incorporated on January 6, 1888.