There's a lovely park/walk along the harbor, and along the way are these informative disks, I guess you'd call them, built into the sidewalks, that tell the history of San Pedro. This one explains how San Pedro was annexed to the city of Los Angeles:
Competition for a deep-water port began in the 1880s as Los Angeles was experiencing phenominal growth. The City founders made sure that the port would be a part of Los Angeles. In November 1907, the Los Angeles City Council approved an ordinance to create the Board of Harbor Commissioners, marking the official founding of the Port of Los Angeles. The development of the port had already started through dredging the main channel, building new wharfs, and constructing the breakwater. The final step, which would consolidate San Pedro and Wilmington with the City of Los Angeles, met with some opposition from harbor residents. However, the package offered by the city to provide for services such as fire stations, schools, a library, a fish market, and a municipally owned ferry was so beneficial that they approved the plan. On August 28, 1909, San Pedro, Wilmington, and Terminal Island were annexed to the City of Los Angeles.