Five weeks ago, Torrance, Calif., Mayor Frank Scotto was celebrating the opening of the city's new athletic fields with officials of Toyota Motor Corp. The city's biggest employer and a prime benefactor had given a half-million dollars toward the project.

This week, Mr. Scotto has had a less pleasant duty to perform: Figuring out how Torrance can fill the 101-acre hole the giant auto maker will leave behind when it vacates its sprawling campus and moves 3,000 jobs to a new North American headquarters in Texas.

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