Over half of Interstate 5 (I-5), the principal north-south route on the west coast of the United States, is located within California. In October 1976, the Department of Transportation classified about 22 miles of I-5 in California's San Joaquin and Sacramento Counties as one of the essential gaps of the Interstate Highway System. At present, about 7 miles of the 22-mile segment have been completed and opened to local traffic, and work on the remaining 13 miles is underway. The entire 22-mile I-5 segment has been controversial, primarily because of environmental issues raised in early 1971 which culminated in legal action. The legal action, which was unsuccessful, was an attempt by environmentalists to halt plans to obtain landfill material (borrow) from the proposed Peripheral Canal for I-5 projects. The legal action did not oppose completion of the highway. Although legislation is pending, neither the State nor the Federal Government has given final approval for Peripheral Canal construction. The State estimates that all work on the segment will be completed by the fall of 1979. The estimated total cost of constructing the segment is $48.5 million, with the Federal share estimated at $43.7 million and the State share estimated at $4.8 million.