The City of Black Diamond has a total area of about 6.66 square miles (17.25 km2), of which 6.02 square miles (15.59 km2) is land while the other 0.64 square miles (1.66 km2) is water, as per the United States Census Bureau.
Black Diamond placed 64th out of 522 places in the state of Washington based on per capita income, one of the more dependable indicators of prosperity.
As of the 2010 census, the city had a population of 4,151 people, 1,546 households, and 1,157 families. There were 689.5 persons per square mile (266.2 inhabitants per km2). There were 1,685 dwelling units at an average density of 279.9 dwelling units per square mile (108.1 dwelling units per km2). The city was 92.0 percent White, 1.2 percent African American, 0.7 percent Native American, 1.2 percent Asian, 0.3 percent Pacific Islander, 1.3 percent other races, and 3.3 percent of those who identified as having 2 or more races. Latino or Hispanic people of any race made up 4.6 percent of the population.
There were 1,546 houses, 37.5 percent of which had kids under the age of eighteen, 62.0 percent of which were married couples, 8.6 percent of which had a female housewife without a husband, 4.3 percent of which had a male householder without a wife, and 25.2 percent of which were non-families. Individuals made up 17.9 percent of all households, while 6.1 percent of all households included someone aged 65 years or older. The typical household contained 2.68 people and the average family contained 3.05.
The city’s median age was 40.4 years. 25.2 percent of people were under the age of 18; 7% were between the ages of 18 and 24; 25.7 percent were between the ages of 25 and 44; 32.1 percent were between the ages of 45 and 64, and 10% were 65 years or older. The city’s gender distribution was 49.8 percent male and 50.2 percent female. (Source: Wikipedia)