Zachary is a city in East Baton Rouge Parish, Louisiana, United States, in the Baton Rouge Metropolitan Statistical Area. The population was 11,275 at the 2000 census.As the population of East Baton Rouge Parish grows, Zachary is changing from a small country town to an affluent suburb of Baton Rouge. Much of Zachary's growth may be attributed to its ranking by the Louisiana Board of Elementary and Secondary Education as the top school district in the state every year since 2005.