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Annexation Methods

This page provides information and links to local government documents related to the various possible methods of annexing territory by Washington cities and towns. For further information on annexation laws and additional resources, see Annexation.


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. The various methods are the following:

Election Method

The election method requires approval of the voters in the proposed annexation area. Although there are other methods of annexation (municipal purpose annexations, annexations of "islands" of unincorporated territory, and the interlocal agreement method) they are available only in limited circumstances and so not often used. A detailed outline of this method is available in our publication Annexation by Washington Cities and Towns, both for code cities and non-code cities.

Example of Petition for Annexation Elections

Examples of Resolutions and Ordinances Calling for Election

Example of Ordinance Approving Annexations after Election

New Petition Method

This method was adopted by the Legislature during the period (2002-04) that the traditional 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.

Examples of Notices and Petitions

Examples of Resolutions and Ordinances

Example of Procedures and Application

Petition Method

The following documents involve the "old" petition method of annexation that was first invalidated on constitutional grounds by the state Supreme Court in Grant County Fire Protection Dist. v. Moses Lake, 145 Wn.2d 702 (2002), and then held valid by the same court in Grant County Fire Protection Dist. v. Moses Lake, 150 Wn.2d 791 (2004). Because the procedures and requirements for this method are slightly different for code cities and for non-code cities (first and second class cities, and towns), the documents below are organized accordingly. For all cities, this method requires the signatures of property owners representing 60% of the assessed value of the area proposed for annexation.

Examples of Initiating Notices for Code Cities

Examples of Annexation Petitions for Code Cities

Example of Initiating Notices for Non-Code Cities

Examples of Ordinances (Petition Method) for Non-Code Cities

Examples of Ordinances (Petition Method) for Code Cities

Unincorporated Islands Method

This method enables the annexation of territory that is wholly or mostly surrounded by incorporated territory. The 2013 Legislature amended, for code cities, the criteria for territory that can be annexed under this method. Per RCW 35A.14.295, an area may be annexed by a code city 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 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 under this method if the city 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, and:

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

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


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, and Thurston. This legislation is codified in RCW 35.13.470-.480 for non-code cities and in RCW 35A.14.460-.470 for code cities.

The following is intended to provide an overview, in question and answer format, of this "island-interlocal" annexation process.

Why did this bill come about?

Legislative history reflects that the bill was a compromise proposal generated by city and county representatives to address concerns regarding "urban subsidies" received by residents in unincorporated "island" areas that are surrounded by one or more cities as well as perceived "cherry-picking" by cities annexing areas with high tax revenues, leaving less valuable property for counties to serve. Presumably, annexations achieved through negotiation of an interlocal agreement should ensure that counties and cities appropriately address their respective fiscal and operational considerations associated with particular annexations.

How is this method of annexing unincorporated "islands" of territory different from the existing method?

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

How is an annexation under this new method initiated?

This method of annexing unincorporated islands of territory actually embodies two alternative procedures, one process - initiated by a county - that can be employed if an initial process - initiated by a city or county - fails. The process is begun by the legislative body of a qualifying city or county (see above) adopting a resolution "commencing negotiations" for an interlocal agreement with the county or a city, as the case may be, for annexation of territory described in the agreement that is within the city's UGA and that has at least 60% of its boundaries contiguous to the annexing city or the annexing city and one or more other cities. After a resolution is adopted, the county and city are to negotiate and try to reach an agreement regarding the annexation.

If, after passage of the resolution, the county and city reach an agreement, the respective legislative bodies must each hold a public hearing, which may be a joint hearing, before actual execution of the agreement. The county and city must, either separately or jointly, publish the text of the agreement at least once a week for two weeks before the date of the hearing(s) in one or more newspapers of general circulation in the area proposed for annexation. Presumably, these publications should also provide notice of the public hearing(s).

How is an annexation under this method completed?

Following the public hearing(s) and adoption of the agreement between the county and city legislative bodies providing for the annexation of the unincorporated island, the city council adopts an ordinance annexing the territory as described in the agreement. The ordinance may provide that the property owners in the annexed area will assume their share of the city's outstanding indebtedness and/or that a specific proposed zoning regulation is adopted for the area. The ordinance must set the date that the annexation is effective, but that date must be 45 days or more following the date of ordinance adoption to accommodate a referendum procedure. The city council must publish notice of the effective date of the annexation at least once a week for two weeks after passage of the ordinance in one or more newspapers of general circulation in the area to be annexed.

Is the annexation ordinance subject to a referendum?

Yes, the annexation ordinance is subject to a referendum election if, within 45 days of adoption of the ordinance, a sufficient referendum petition is filed with the city council. A referendum petition is sufficient if it is signed by registered voters representing not less than 15% of the number of votes cast at the last state general election in the area to be annexed. If a sufficient petition is filed, an election on the annexation is to be held at a general election if it is within 90 days of the filing of the petition or at a special election called for that purpose according to RCW 29A.04.330. The election is held only within the area subject to annexation and is decided by majority vote.

What if a city and county cannot reach agreement on annexing the unincorporated island?

The county may initiate the annexation process with another city that has boundaries contiguous to the unincorporated island if the county initiated the annexation process by resolution, as above, and:

  • the affected city rejected the proposed annexation or declined to enter into an agreement; or
  • 180 days have passed since the county adopted the resolution and no agreement has been reached and neither the county or the city have, after a public hearing, passed a resolution extending the negotiation period.

However, the negotiation period may be extended at the option of either the city or county by adoption of a resolution extending that period by one or more six-month periods, if a public hearing is held and findings of fact supporting the extension are adopted prior to each extension.

The process then goes on exactly as in the original process above, although in this case it is only the county that, by resolution, can initiate the process. Annexation under this process is also subject to referendum.

May a city, under this second process, annex territory that is within another city's urban growth area or within an "urban service area" or "potential annexation area" designated for another city?

Apparently so. A separate provision of this bill amended the GMA and authorizes the designation in a county comprehensive plan of "urban services areas" or "potential annexation areas" for specific cities within an urban growth area. See SHB 1755, Sec. 5, amending RCW 36.70A.110(7). Some counties have previously designated such areas within urban growth areas that border more than one city. If the territory proposed for annexation under this second process has been designated as part of an "urban service area" or "potential annexation area" for a specific city (i.e., not the annexing city under this second process) or if it lies within another city's urban growth area, or if the urban growth area territory proposed for annexation has been designated in a written agreement between the county and a specific city for annexation to that city, the city that the county negotiates with under this second process may still annex that territory as long as that designation receives "full consideration" before this second process can be initiated. What exactly may be necessary to satisfy this "full consideration" requirement remains to be seen.

May a county, under this second process, reach agreement with more than one city concerning annexation of the same territory, and, if so, what happens in that event?

Yes, a county may reach agreement with more than one city to annex the same unincorporated island, thereby throwing to the voters in that territory the choice of which city, if any, to annex to. The ballot for this election is to provide voters with the choice of whether or not to annex to a city and, for those voters wanting to annex, the choice of which city to annex to. If a majority of voters chose annexation, the area will be annexed to the city receiving the most votes among those voting in favor of annexation. The rules governing this election are otherwise those for an annexation by the election method. See RCW 35.13.070 and RCW 35.13.080 (for non-code cities); and RCW 35A.14.070 for code cities. The county bears the cost of this election.


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. For code cities, territory can be annexed by this method only if it is owned by the city. For non-code cities, territory can be annexed by this method 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.


Interlocal Agreement Method for Annexation of Areas Served by Fire Districts

Under this method authorized by the 2009 Legislature, a city, the county in which the city is located, and a fire district or districts can enter into an interlocal agreement that describes the annexation area and the goals of the agreement, including such matters as: the transfer of revenues and assets between the fire protection district(s) and the city; the 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; and revenue sharing, if any. If only the city and the county reach agreement on the enumerated goals, the annexation may still proceed.

Annexations under this method are subject to potential referendum, but, if the process was started by the city sending the statutory notice to the district and the county prior to July 28, 2013, an annexation under this method, where all the parties reach agreement, is not subject to referendum. See RCW 35.13.238 for non-code cities and RCW 35A.14.480 for code cities.


Annexation of Federal Areas

The procedures for annexing land that is owned by the federal government are found in RCW 35.13.185 for first class cities, in RCW 35.13.190-.210 for second class cities and for towns, and in RCW 35A.14.310-.320 for code cities.


Recommended MRSC Resources

  • Annexation by Washington Cities and Towns – This publication outlines the pro and con arguments for annexation, the consequences of annexation, reviews in detail the methods for annexation, and discusses the role of boundary review boards in the annexation process.
  • Annexation Blog Posts – Provides a list of annexation blog articles.
  • Annexation Inquiries – Browse questions and answers on special considerations regarding annexations.

Last Modified: October 09, 2019