City plans have existed throughout the history of urban development as a means to organize space and ensure that essential ceremonial and communal functions could be accommodated. Beginning in the early 20th Century, and in response to the detrimental effects of rapid urbanization (inadequate housing, poor sanitation, industrialization, etc.), city plans emphasized a compelling vision of a future (the "city beautiful"; the "garden city") intended to engage the public, build civic pride, and encourage long-term investments and decision-making that would ultimately realize the goals of the plan. By the 1920s states began adopting planning and zoning enabling laws that allowed local governments to regulate the use and development of individual properties under the premise of protecting public health, safety, and welfare. These laws typically made zoning ordinances the primary tool for guiding growth and development, while general (or comprehensive) plans were considered to be optional, advisory documents. That is still true in many states, even today.
In 1971, the state of California amended its Government Code to make General Plans mandatory for every city and county in the state and further, and more significantly, required all local land use approvals to be consistent with the jurisdiction's General Plan. In 1990, the California Supreme Court firmly established the General Plan as the pre-eminent statement of local planning policy governing future growth and development, calling it "the constitution for all future development." On-going changes in state law and successive interpretations by the courts continue to add to the scope and responsibilities of the General Plan. However, in its purest form, the General Plan is the link between the expressed values and vision of the community and the resulting public process and decision-making that affect the physical, social, environmental, and economic character of the community.