Of the county's 2,751,796 total residents (as of 2017), approximately 44% live in unincorporated areas, the majority of which are heavily urbanized. These residents are part of the Unincorporated Municipal Services Area (UMSA). For these residents, the County fills the role of both lower- and upper-tier government, the County Commission acting as their lower-tier municipal representative body. Residents within UMSA pay an UMSA tax, equivalent to a city tax, which is used to provide County residents with equivalent city services (police, fire, zoning, water and sewer, etc.). Residents of incorporated areas do not pay UMSA tax.