A Standard Metropolitan Statistical Area (SMSA) is a geographic region defined by the United States Office of Management and Budget (OMB) for use in the collection and dissemination of statistical data. SMSAs are defined based on population and economic criteria, and are used to group together cities and their surrounding areas that have significant social and economic ties. The OMB defines MSAs as consisting of one or more counties and containing at least one city with 50,000 or more inhabitants.