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Annexation Methods by Cities and Towns

This page provides a general overview of the various possible methods of annexing territory by cities and towns in Washington State.

It is part of MRSC's series on Annexation in Washington State.

Overview

The methods by which cities and towns can annex territory are governed strictly by state law, and they vary somewhat by city classification. The methods of annexation by code cities are in chapter 35A.14 RCW, while the methods of annexation by non-code cities are in chapter 35.13 RCW.

Note that cities and towns located in counties that plan under the Growth Management Act may annex only property that is located within their designated urban growth areas.

Of all the methods of annexation available, the sixty percent petition method is by far the most frequently used. Cities have found the election method to be extremely cumbersome. Because of this and the expense of conducting an election, annexation elections are infrequent. Statutes authorizing summary annexations for municipal purposes are much more straightforward but may be utilized only when a legitimate municipal reason for annexation can be shown, such as the use of the annexed land for a city park or water tower. Finally, the statutes authorizing the annexation of federal areas are of very limited application.

Detailed descriptions of all annexation methods are available in our publication Annexation by Washington Cities and Towns, both for code cities and non-code cities (first and second class cities, and towns).

For a general overview of each of the methods of annexation, including examples for each method, see our summaries below. Note that the examples are organized according to city classification, as the procedures vary somewhat.

60% Petition Method (Direct Petition Method)

The 60% petition method, or direct petition method, is the most commonly used method of annexation by cities and towns in Washington State. It requires the signatures of property owners representing 60% of the assessed value of the area proposed for annexation.

The 60% petition method is sometimes referred to as the "old" petition method of annexation. In 2002, the Washington State Supreme Court invalidated this method on constitutional grounds in Grant County Fire Protection Dist. v. Moses Lake (2002). Not long afterward, the same court reversed itself and determined this method was valid in Grant County Fire Protection Dist. v. Moses Lake (2004). During the period it had been deemed unconstitutional, the legislature adopted a new alternative petition method that was consistent with the court’s 2002 decision. Both the “old” 60% petition method and the “new” alternative petition method continue to be options today.

The 60% petition method is codified at:

The 60% petition method is initiated by an initiating notice signed by 10% of the property owners (RCW 35A.14.120 for code cities; RCW 35.13.125 for non-code cities and towns). If the city council accepts the initial annexation proposal, the initiating parties may draft and circulate a petition for signatures.

Examples of Initiating Notices 

Below are examples from code cities:

Below is an example from a non-code city:

Examples of Annexation Petitions 

Below are annexation petition examples from code cities:

Examples of Ordinances 

Below are examples from code cities:

Below are examples from non-code cities and towns:

Alternative Petition Method

This method was adopted by the Legislature during the period (2002-04) that the traditional 60% petition method had been declared unconstitutional by the state Supreme Court. It requires the support of property owners representing a majority of the area proposed for annexation and of a majority of the voters in the area.

The method is codified at:

Examples of Notices and Petitions

Below are some examples from code cities:

Below is an example from a non-code city:

Examples of Resolutions and Ordinances 

Below are examples from code cities:

Below is an example from a non-code city:

Examples of Procedures and Application 

Below is an example from a non-code city:

Election Method (Initiated by Petition or by Resolution)

The election method requires approval of the voters in the proposed annexation area. Election method annexations may be initiated either by a petition signed by a percentage of the voters living in the area to be annexed who voted in the last election (10% if a code city, or 20% if a non-code city or town), or by city council resolution. Both election methods (initiated by petition or resolution) are nearly identical except for the first few steps. Cities have found the election method to be cumbersome and expensive. Because of this, annexation elections are much less common than the petition methods.

The election method is codified as follows:

Note: If the election method of annexation is to be used, a word of caution is necessary. Since a ballot proposition is involved, the public information program must be tailored to comply with RCW 29B.45.010, which generally prohibits the use of public funds in promoting or opposing a ballot measure. See MRSC’s page Use of Public Facilities in Election Campaigns.

In short, cities and towns should not publish promotional material urging a favorable vote in an annexation election. City employees should not use city facilities and resources to actively attempt to influence voter response. However, a distinction may be drawn between promoting an annexation and merely providing factual information directed at enabling voters to make their own decisions based on factual data, rather than uninformed speculation. The annexation statutes specifically authorize a city or town to “provide factual public information on the effects of a pending annexation.” See RCW 35.13.350, 35.21.890, and 35A.14.550, along with WAC 390-05-271 and 390-05-273.

If a private citizen group is involved, any legal ambiguities as to the information that can be provided may be avoided when the citizens, rather than the city, prepares, finances, publishes, and distributes annexation information pamphlets. Citizen groups may not only provide factual information but also advocate positions. Any such group would be well advised to check with the Public Disclosure Commission early in its formation stages, to learn whether any campaign financing information or forms will be expected.

Examples of Resolutions and Ordinances Calling for Election 

Below are some examples from code cities:

  • Bothell
  • Sammamish
    • Resolution No. R2014-602 (2014) – Declaring the city’s intent to annex an unincorporated area of King County and calling for an election to be held submitting to the voters within the area of the proposal for annexation.
    • Resolution No. R2015-615 (2015) – Requesting that the King County director of elections hold a special election for the purpose of placing on the ballot a proposition concerning the annexation of certain property.
    • Ordinance No. O2015-393 (2015) – Annexing certain property after election.

Unincorporated Islands Method

This method enables the annexation of territory that is wholly or mostly surrounded by incorporated territory and is a much shorter process than required for the petition and election methods of annexation. This method is available to cities and towns planning under the Growth Management Act (GMA), and the territory must be within a designated urban growth area. The criteria for annexing these "unincorporated islands" differs somewhat between code and non-code cities and towns. A city council may initiate annexation under this method by resolution.

Per RCW 35A.14.295, a code city may annex an area under the unincorporated island method of annexation if:

  • The area is less than 175 acres and all its boundaries are contiguous to the city (i.e., it is entirely surrounded by the city); or
  • The area is of any size and has at least 80% of its boundaries contiguous to the city, it contains residential property owners, and it is within the same county and urban growth area as the city, and the code city is required to plan under the Growth Management Act (GMA).

Annexations under this method are subject to potential referendum (RCW 35A.14.297-.299).

The authority provided to non-code cities and towns under this method is more limited than for code cities. Per RCW 35.13.182, an area may be annexed by a non-code city or town under this method if the city or town was planning under the GMA as of June 30, 1994, the area contains residential property owners, the area is within the same county and urban growth area of the city or town, and:

  • The area is less than 100 acres and has at least 80% of its boundaries contiguous to the city or town; or
  • The area is of any size, has at least 80% of its boundaries contiguous to the city or town, and it existed before June 30, 1994.

Annexations under this method by non-code cities or towns are also subject to potential referendum (RCW 35.13.1821).

Examples of Resolutions and Ordinances 

Below are some examples from code cities:

Unincorporated Island-Interlocal Agreement Method

This method provides an "alternative" method of annexing islands of unincorporated territory through use of interlocal agreements. However, this "island-interlocal" method of annexation is only available to cities and towns located in counties that are subject to the "buildable lands" review and evaluation program under the Growth Management Act (GMA).

These counties are: Clark, King, Kitsap, Pierce, Snohomish, Thurston, and Whatcom.

This unincorporated island-interlocal agreement method is codified in:

Unlike the existing method of annexing unincorporated "islands" of territory, which requires the proposed annexation area to have at least 80% of its boundaries contiguous to a single city or town (RCW 35.13.182 and 35A.14.295), the proposed annexation area under this "island-interlocal" method need have only 60% of its boundaries contiguous to a city or town, or to more than one city or town. As with all annexations in counties subject to the GMA, the proposed annexation area must be within an urban growth area (UGA).

Annexations under this method are subject to potential referendum.

Tax Credit

In 2023, the legislature revived and updated the annexation tax credit program to encourage annexation of remaining portions of unincorporated UGAs. See RCW 82.14.415.

The tax credit is triggered by an annexation interlocal agreement between a city and county pursuant to RCW 35A.14.472, 35A.14.296, or 35.13.470. Cities can receive:

  • 0.1% sales tax credit for annexations of more than 2,000 in population but less than 10,000.
  • 0.2% sales tax credit for annexations of more than 10,000 in population.

Examples of Resolutions and Ordinances

Below are some resolution examples from code cities:

  • Fife Resolution No. 1917 (2020) – Initiates the process of creating an interlocal agreement with Pierce County for annexing unincorporated areas into Fife. 
  • Lake Stevens Resolution No. 2019-07 (2019) – City Council resolution authorizing the mayor to sign an interlocal agreement with Snohomish County approving the Southeast Island annexation. 

Below is an ordinance example involving a non-code city:

  • Pierce County Ordinance No. 2021-81s (2021) – Final ordinance approving an interlocal agreement with the City of Tacoma to annex the unincorporated "Manitou Potential Annexation Area." Includes the Annexation Agreement.

Municipal Purpose Method

This method allows the annexation of property that is to be used for a "municipal purpose" and is accomplished by city council action alone. Notably, it can be used to annex territory that is not contiguous to existing boundaries.

Territory can be annexed by this method:

  • For code cities, only if it is owned by the city (RCW 35A.14.300).
  • For non-code cities and towns, if the territory is either owned by the city or if all of the property owners in the territory give their written consent to the annexation (RCW 35.13.180).

Examples of Ordinances

Below are examples from code cities:

Below are examples from non-code cities:

Interlocal Agreement Methods (Code Cities ONLY)

There are two recent statutes that address annexation by code cities by interlocal agreement: 

MRSC interprets these statutes as establishing two separate methods to annex via interlocal agreement. They both apply to code cities but include some different requirements. The interaction between the two statutes is somewhat unclear and a city should consult its city attorney before proceeding with either method.

Interlocal Agreement Method Following RCW 35A.14.472

In 2021, the legislature authorized code cities, as provided in RCW 35A.14.296(2), to collaborate with the county (or counties) to form an interlocal agreement regarding annexation of unincorporated territory within the urban growth area (RCW 35A.14.472). The interlocal agreement formation process must include procedures for public participation and may only be executed after notice on each legislative body’s website for four weeks and a public hearing by each legislative body, separately or jointly. The agreement must also address:

  • A balancing of annexations of commercial, industrial, and residential properties so that any potential loss or gain is considered and distributed fairly as determined by tax revenue;
  • Development, ownership, and maintenance of infrastructure;
  • The potential for revenue-sharing agreements. 

Interlocal Agreement Method Following RCW 35A.14.296

In 2020, the legislature authorized code cities to annex unincorporated territory pursuant to an interlocal agreement between the city and county (RCW 35A.14.296), subject to the following requirements:

  • Notice of Annexation to Impacted Special Purpose Districts/City
    • The city must provide written notice to the governing authorities of the following impacted special purpose districts and adjacent city (if applicable):
      • Fire protection districts, regional fire protection service authorities, water-sewer districts, and transportation benefit districts within the proposed annexation area;
      • Any city adjacent to the proposed annexation area where the sole access or majority of egress and ingress of the area is served by the transportation network of the impacted city.
    • The impacted districts or city will have 30 days from the date of such notice to notify the code city whether it would like to be a party to the interlocal agreement with the city and county. If timely notice is provided, the notifying district(s) and/or city must be included as a party to the agreement.
    • Any impacted district or city may disagree with the annexation, in which case, the annexation may not proceed using this method.
  • Public Hearing
    • A public hearing must be held by each legislative body, either jointly or separately, before an interlocal agreement is executed.
    • Notice of availability of the agreement must be published at least once a week for four weeks prior to the hearing on the city and county website (if available), and in a newspaper of general circulation within both the code city and the territory proposed for annexation. The notice must also indicate if the annexation would provide for assumption of indebtedness or adoption of proposed zoning regulations.
  • Interlocal Agreement
    • The boundaries and effective date of the annexation are decided jointly and set forth in the interlocal agreement.
    • The date of the public hearing must be set forth in the interlocal agreement.
    • The interlocal agreement must ensure that for a period of five years after the annexation, any residentially-zoned parcels retain their residential zoning, and the area’s minimum gross residential density must not be reduced below the density allowed prior to annexation.
    • An interlocal agreement may be amended to add additional territory.
  • Annexation Ordinance
    • After the public hearing, the city must adopt an ordinance to effect the annexation. An annexation agreement may include phased annexation of territory. If it does, an ordinance must be adopted at each phase of annexation.
    • A certified copy of the annexation ordinance must be filed with the board of county commissioners of the county in which the annexed property is located.

Tax Credit

In 2023, the legislature revived and updated the annexation tax credit program to encourage annexation of remaining portions of unincorporated UGAs. See RCW 82.14.415.

The tax credit is triggered by an annexation interlocal agreement between a city and county pursuant to RCW 35A.14.472, 35A.14.296, or 35.13.470. Cities can receive:

  • 0.1% sales tax credit for annexations of more than 2,000 in population but less than 10,000.
  • 0.2% sales tax credit for annexations of more than 10,000 in population.

Examples of Interlocal Agreement Annexations 

Below are examples of interlocal agreement annexations that follow RCW 35A.14.296:

Interlocal Agreement Method for Annexation of Areas Served by Fire Districts

This is a method of annexation adopted by the legislature in 2009 that may be employed where a city or town is proposing to annex territory within one or more fire protection districts (RCW 35A.14.480 for code cities and RCW 35.13.238 for non-code cities and towns). Under this method, a city or town, the county in which the city or town is located, and a fire district or districts may enter into an interlocal agreement that describes the annexation area and the goals of the agreement, including such matters as:

  • Transfer of revenues and assets between the fire protection district(s) and the city or town
  • Impact of annexation on the level of fire protection and emergency medical service in both the unincorporated and incorporated area
  • Community involvement in the process
  • Revenue sharing, if any

If only the city or town and the county reach agreement on the enumerated goals, the annexation may still proceed.

Annexations under this method are subject to potential referendum.

Examples of Interlocal Agreements 

Below are examples from code cities:

Below are examples from non-code cities:

Annexation of Federal Areas

The procedures for annexing land that is owned by the federal government are found in:

Examples of Ordinances

Below are examples from code cities:

Boundary Line Adjustments Associated with Rights-of-Way or Split Parcels

State law provides a process for adjusting existing or proposed city boundary lines to avoid a situation where a common boundary line is or would be located within a right-of-way of a public street, road, or highway (RCW 35.13.300-.340). The process also applies to the situation where two cities are separated or would be separated only by the right-of-way of a public street, road, or highway, other than where a boundary line runs from one edge to the other edge of the right-of way (RCW 35.13.300).

The process is available to all cities and towns, including code cities.

Boundary adjustments can also be made where a portion of a parcel of land is located partially within and partially without city boundaries (or a parcel is split between two cities), where the property owner requests the adjustment and the process at RCW 35.13.340 is followed.

For a county right-of-way located on city boundaries, the city and county can agree to revise the corporate boundaries to include the right-of-way. See RCW 35A.21.210 (code cities) and RCW 35.21.790 (any city or town).

Examples of Resolutions and Ordinances

  • Fife Resolution No. 1856 (2019) – Authorizes city manager to execute boundary line adjustment with Milton under RCW 35.13.310 due to road realignment and reconstruction that resulted in common boundary being within the right-of-way; includes interlocal agreement
  • Kirkland Resolution R-5249 (2017) – Authorizes city manager to execute boundary line adjustment with Bellevue under RCW 35.13.310 due to misalignment of boundary line and existing infrastructure; includes interlocal agreement.
  • Snohomish County Ordinance No. 19-082 (2020) – Authorizes county executive to execute boundary line adjustment with Everett under RCW 35.21.790, including transfer of real property by quitclaim deeds, to fix ambiguities related to right-of-way and facilities. Includes interlocal agreement.
  • West Richland Resolution No. 03-24 (2024) – Authorizes mayor to execute boundary line adjustment with Benton County under RCW 35A.21.210 to revise boundary that falls within right-of-way; includes interlocal agreement.
  • Yakima Resolution No. R-2017-120 (2017) – Authorizes city manager to execute boundary line adjustments with Union Gap under RCW 35.13.310 at ten different locations where the boundaries are within the right-of-way; includes interlocal agreement and map exhibits.

Last Modified: January 06, 2026