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Municipal Incorporation

This page provides an overview of the municipal incorporation process in Washington State, including related statutes, court decisions, and examples of incorporation feasibility studies.


Under Washington law, an area can incorporate as a city if it has a minimum of 1,500 inhabitants. If within five air miles of the boundaries of a city with a population of 15,000 or more, the area must have a minimum of 3,000 inhabitants.

The basic procedure to incorporate is set out in chapter 35.02 RCW, and it includes a petition requirement, review by a boundary review board or the county legislative body in counties without a board, and an election. If the voters approve the proposed incorporation, a primary election to nominate candidates for city council (and, in mayor-council cities, a mayor) and then an election to select the city council must be held. The new city must officially incorporate, at a date set by the initial city council, within 360 days of the incorporation election.

For a detailed description of the municipal incorporation process and how to establish a new city government, see the following MRSC publications:

  • Municipal Incorporation Guide – Designed to assist residents of unincorporated communities in Washington to understand the process by which a community can become incorporated as a city and to help a community decide whether to incorporate.
  • The New City Guide – Provides information to aid communities in establishing a viable, functioning city government after incorporation.

Fifteen cities have incorporated in Washington State since 1990. During the two decades prior to 1990, only one city had incorporated in the state. This recent surge in incorporation activity, which also included a number of failed incorporation attempts, can be attributed to a great extent to rapid population growth, particularly in the Puget Sound region. The increasing urbanization and sprawl that has resulted has caused many communities to consider incorporation as a means of exercising local control over community character and destiny.


  • Washington State Const. art. 11, § 10 – Incorporation of Municipalities. This constitutional provision establishes the basic authority for cities and towns to incorporate and for the state legislature to enact laws to govern the process of incorporation.
  • Ch. 35.02 RCW – Incorporation Proceedings. This chapter contains the basic statutory procedures for incorporation as a city in Washington State. It also establishes the legal authority and power of a city during the "interim period," the period between the election of the initial city council and the official date of incorporation. In addition, it addresses issues relating to the continued provision of municipal services after incorporation.
  • Ch. 36.93 RCW – Local Government Organization - Boundaries - Review Boards. Proposed incorporations are "reviewed" by a boundary review board in counties in which boards have been established. Currently, 15 of the state's 39 counties have boundary review boards. This RCW chapter provides the procedures and guidelines for boundary review board review of incorporations and of other processes, such as annexations, that alter municipal boundaries.

Miscellaneous Incorporation Documents

Examples of Incorporation Feasibility Studies

Court Decisions

Vashon Island v. Boundary Review Bd., 127 Wn.2d 759 (1995) – The state supreme court concluded that there is no constitutionally protected right to have an incorporation petition considered under the law existing at the time a notice of intent to seek incorporation was filed with a boundary review board.

Last Modified: October 28, 2019