Historic properties are identified primarily through the completion of historic property surveys. These surveys may be conducted by city staff or by an outside entity. Each survey looks at properties within a specific geographical area, which may be as small as a single city block or as large as the entire city. Depending on the purpose of the survey, it may attempt to identify every eligible historic property in the survey area or it may focus on the eligibility of properties relating to a particular theme (such as commerce, agriculture, or ethnic heritage). With some exceptions, historic property surveys generally consist of a summary of the survey methodology, a written report with one or more historic contexts, and an inventory of the historic properties identified in the survey accompanied by maps, photographs, and recommendations of eligibility.