Alameda County | 25,133 followers on LinkedIn. One of 58 counties in California, Alameda County is home to over 1.5 million people living in 14 incorporated cities as well as in six unincorporated communities and rural areas throughout the 813 square miles of the County. The County enjoys a varied geography ranging from urban marinas to rolling open spaces to hillside lakes and streams. Characterized by rich diversity and culture, Alameda County takes pride in being one of the most ethnically diverse regions in the Bay Area and the nation.