San Lorenzo California is an in the unicorporated area of Alameda County in the East Bay.
Per the Census Bureau in 2000, there were 21,898 people, 7,500 households, and 5,677 families There are approx 7,893.4 people per square mile
There were 7,500 households, out of which 34.7% had children under the age of 18 living with them, 58.1% were married couples living together, 12.6% had a female householder with no husband present, and 24.3% were non-families. 19.1% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older. The average household size was 2.92 and the average family size was 3.34.
In the CDP the population was spread out with 25.2% under the age of 18, 8.0% from 18 to 24, 29.5% from 25 to 44, 21.3% from 45 to 64, and 16.0% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 94.0 males. For every 100 females age 18 and over, there were 91.3 males.
The median income for a household in the CDP was $56,170, and the median income for a family was $61,787. Males had a median income of $43,626 versus $34,531 for females.