The population density was 3,214.9 people per square mile (1,241.3/km²). The racial makeup of Alameda was 37,460 (50.8%) White (U.S. Census), 23,058 (31.2%) Asian (U.S. Census), 4,759 (6.4%) African American (U.S. Census), 426 (0.6%) Native American (U.S. Census), 381 (0.5%) Pacific Islander (U.S. Census), 2,463 (3.3%) from Race (United States Census), and 5,265 (7.1%) from two or more races.  Hispanic (U.S. Census) or Latino (U.S. Census) of any race were 8,092 persons (11.0%).There were 30,123 households, out of which 9,144 (30.4%) had children under the age of 18 living in them, 13,440 (44.6%) were opposite-sex married couples living together, 3,623 (12.0%) had a female householder with no husband present, 1,228 (4.1%) had a male householder with no wife present. There were 1,681 (5.6%) POSSLQ, and 459 (1.5%) same-sex married couples or same-sex partnerships. 9,347 households (31.0%) were made up of individuals and 2,874 (9.5%) had someone living alone who was 65 years of age or older. The average household size was 2.40. There were 18,291 family (U.S. Census) (60.7% of all households); the average family size was 3.06.. What was the second largest type of household?