Dianne McKenna, a native of Pennsylvania, moved to the Silicon Valley in the 1960's. In 1977, she received her Master's Degree in Urban and Regional Planning from San Jose State University. In that same year, McKenna was elected to the Sunnyvale City Council, where she served until 1984, with exception of the terms 1980-1981 and 1982-1983, when she was elected as the Mayor of Sunnyvale.

In 1985, McKenna became the fifth woman elected to the Santa Clara County Board of Supervisors, a position that she held until 1996. McKenna led numerous efforts to relieve traffic congestion, enhance mobility, and improve air quality. She shepherded development of the county's first transportation demand management ordinance. McKenna led the effort to form the county's first Congestion Management Agency, a multi-jurisdictional body responsible for finding cooperative solutions to transportation, land­use planning, and air quality problems. She developed and secured voter approval of a plan to merge the Transit District with the Congestion Management Agency to create the Valley Transportation Authority, streamlining countywide transportation planning and decision making.

McKenna was a founding member of the Peninsula Corridor Joint Powers Board, which operates the CalTrain commuter rail service between Gilroy and San Francisco. Her leadership in the transportation field culminated in her service as 1995 chair of the Metropolitan Transportation Commission, the transportation planning agency for the nine-county San Francisco Bay Area.

McKenna also initiated several major efforts to improve services for children and families. First, she instituted a successful public/private partner­ship to construct a new $12.4 million children's shelter in Santa Clara County. The New Children's Shelter, due to open in 1995, represents a major step in providing safe and homelike care for the county's abused and neglected children. Second, she established the Children and Youth Joint Conference Committee of the board of supervisors to integrate and coordinate services for children and families. In 1994, she initiated the School-Linked Services Plan to deliver comprehensive county services at school sites or community facilities. McKenna is a founding member of Kids In Common, a nonprofit corporation that brings the public, private, and nonprofit sectors together to in­crease human and financial resources available to children and families.

McKenna initiated recycling efforts as the Chair of the Solid Waste Commission of Santa Clara County, and in 1994, led the General Plan Review Advisory Committee to complete its work of reviewing and updating land use plans and policies.

McKenna retired from public office in 1997, but remained active in numerous civic, educational, and environmental organizations.