From early exploration in 1608 through hopes for 2212, oyster reefs in the Chesapeake Bay shaped the region’s ecology, economy, and future. Oysters were once so abundant that reefs were exposed at low tide and could hazard navigation, and Native Americans and American colonists depended on them for food, with some oysters in the 1600s reaching 13 inches long. Their filter feeding helped create exceptional water clarity, with a single oyster filtering about 50 gallons per day and the Bay’s entire water volume historically filtered about every seven days, while the reefs also provided vital habitat for aquatic life. In the late 1800s, oyster harvesting peaked at about 20 million bushels each year, and the shell foundations of the reefs were dredged away and used in roads, mortar, iron furnaces, fertilizer, and whitewash, depleting in less than 100 years what had accumulated over thousands of years. In the early 1900s, oyster populations declined as harvests exceeded reproduction and spat lost surfaces on which to grow. By the 1960s, the introduced diseases MSX and Dermo caused up to 90 percent mortality in some areas, while sediment from increasingly severe storms blanketed oysters on the Bay bottom. Today the Chesapeake Bay oyster population stands at an estimated 1 percent of historical levels, water quality and clarity have declined, biodiversity has been reduced, and filtration that once took about seven days now takes about a year. Restoration efforts include placing reef balls to provide surfaces for oyster spat and habitat for fish, crabs, and other organisms; the first reef balls were placed at the Memorial Stadium Reef site at Gales Lump in the Upper Chesapeake Bay in 2002, and Bill Huppert, the Maryland Saltwater Sportfishing Association, and thousands of volunteers have helped build more than 1500 reef balls. With an estimated lifespan of 500 years, these reef balls may help form the foundation of revitalized reefs and support a healthier, more diverse Chesapeake Bay in the future.