Brookfield is a city that borders the western side of the City of Milwaukee, Wisconsin and is located in Waukesha County, Wisconsin. It had a population of 37,920 in the 2010 census. Brookfield is the second largest city in Waukesha County, and the leading commercial suburb of Milwaukee. The City of Brookfield was formed in 1954 from the Town of Brookfield, a portion of which still survives along the city's western edge. Brookfield shares the Elmbrook School District with the Town of Brookfield, with Village of Elm Grove and with a small section of City of New Berlin. A very small section of the city is served by the Waukesha School District.
According to the United States Census Bureau, the city has a total area of 27.3 square miles (70.6 km²), of which, 27.2 square miles (70.4 km²) of it is land and 0.1 square miles (0.2 km²) of it (0.26%) is water. The sub-continental divide passes through Brookfield; on the eastern side of this divide, easily marked by the crest at Calhoun Road and Capitol Drive, water flows to Lake Michigan on its way to the Gulf of Saint Lawrence; on the western side of this divide, water flows to the Fox River of Illinois and Wisconsin on its way to the Mississippi River and the Gulf of Mexico.
There is a heron rookery on a site northwest of Capitol Drive and Brookfield Road.