The old port town of Alviso, nestled in the southernmost point of San Francisco Bay, was busy long before the gold rush. It began in the 1700s as a landing for Mission Santa Clara, where Californios drove oxcarts heavy with cowhides and tallow to load aboard ships bound for New England and Europe. Later immigrants disembarked from paddle-wheel steamers to establish farms and businesses throughout the South Bay. Quicksilver from the New Almaden mines,...