In the 21 years following 1970, Santa Rosa grew by about 3,000 residents a year—triple the average growth during the previous twenty years.
Santa Rosa 2010, the 1991 General Plan, called for a population of 175,000 in 2010.
In 1867, the county recognized Santa Rosa as an incorporated city and in 1868 the state officially confirmed the incorporation, making it officially the third incorporated city in Sonoma County, after Petaluma, incorporated in 1858, and Healdsburg, incorporated in 1867. The city continued to grow when other early population centers declined or stagnated, but by 1900 it was being overtaken by many other newer population centers in the San Francisco Bay Area and Southern California.
According to a 1905 article in the Press Democrat newspaper reporting on the "Battle of the Trains", the city had just over 10,000 people at the time.
Upon the arrival of Europeans, the Pomos were decimated by smallpox brought from Europe, and by the eradication efforts of Anglo settlers. The first known permanent European settlement of Santa Rosa was the homestead of the Carrillo family, in-laws to Mariano Guadalupe Vallejo, who settled the Sonoma pueblo and Petaluma area.