Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Washington County is a county in the U.S. state of Wisconsin. As of 2000, the population was 117,493. Its county seat is West Bend.According to the U.S. Census Bureau, the county has a total area of 436 square miles (1,129 km²), of which, 431 square miles (1,116 km²) of it is land and 5 square miles (13 km²) of it (1.16%) is water.In the county, the population was spread out with 26.70% under the age of 18, 7.20% from 18 to 24, 31.50% from 25 to 44, 23.40% from 45 to 64, and 11.20% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 99.50 males. For every 100 females age 18 and over, there were 97.00 males.