Everyone loves a good mystery especially when it is in one's own back yard! Author Carol Jensen, the Brentwood Press, and the East County Historical Society team up to learn more about the families, successes, and lives of early east Contra Costa County residents. Local citizens are challenged to identify people and locations throughout the community as captured in postcard images from the early 20th century. The response is insightful, often witty, and illustrates the interesting lives of emigrants settling the beautiful California Delta. Presented in Challenge (Mystery) and Solution (History) format, readers are asked to share their insights regarding the postcard image, sender, or recipient. Responses are gathered, sifted, and presented in subsequent newspaper editions. This compilation of 15 postcard inspired articles was a monthly feature of the Brentwood Press from 2010 to 2012. History Mystery Postcards from the California Delta depicts life in small town California and provides insights into early 20th century life. Postcard collectors, mystery sleuths, and social/cultural history enthusiasts will enjoy revisiting life as it was experienced the century past. The Brentwood Press and East Contra Costa Historical Society are pleased to play a part in preserving local heritage.