The plan, made public Tuesday, would develop 3,500 acres but retain more than 30 percent of the area east of Sacramento as open space.
Plans include almost 12,000 residential units and more than 7,500 jobs, along with a regional mall. The city had 69,000 residents in 2006, according to the state Department of Finance.
The plans must be put to public review and the annexation is expected to take more than two years. Development is scheduled to begin in 2010.
Seven owners control the land. Among them are partnerships that include Angelo K. Tsakopoulos, Sacramento's largest developer.
Finding enough water for the new area may be a problem, although City Manager Kerry Miller said the city has good prospects of obtaining an adequate supply.
Mike McKeever, executive director of the Sacramento Area Council of Governments, said the plan does a good job of protecting natural resources and encouraging walking, biking and public transit.
But a Folsom resident who opposes the development said he and other residents plan to put a measure on the ballot giving voters a chance to reject the expansion idea.