Mason County is a county located in the State of Washington. As of the 2010 census, the population was 60,699. The county seat is at Shelton, the county's only incorporated city. Mason County has several school districts.
There were 18,912 households out of which 28.90% had children under the age of 18 living with them, 56.90% were married couples living together, 9.20% had a female householder with no husband present, and 29.20% were non-families. 23.30% of all households were made up of individuals and 9.90% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 2.89.
In the county, the population was spread out with 23.50% under the age of 18, 7.70% from 18 to 24, 26.50% from 25 to 44, 25.80% from 45 to 64, and 16.50% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 107.00 males. For every 100 females age 18 and over, there were 107.30 males.
The median income for a household in the county was $39,586, and the median income for a family was $44,246. Males had a median income of $37,007 versus $25,817 for females. The per capita income for the county was $18,056. About 8.80% of families and 12.20% of the population were below the poverty line, including 17.30% of those under age 18 and 4.90% of those age 65 or over.