Annual Housing Development Estimates by Jurisdiction

PSRC utilizes assessor data extracts for King, Kitsap, Pierce, and Snohomish counties to estimate housing development at the parcel level for each year in this time series. The methodology utilizes variables that identify Residential Uses, Number of Units, and Number of Buildings together with a Year Built variable to estimate new housing units built annually by structure type. The most current vintage of residential assessor records are then related back to a base year record set to determine what type of development took place on a given parcel. Development activity types tracked are: 'New Development', 'Redevelopment', and 'Rebuild/Remodels'. For Redevelopment and Rebuild/Remodels, base year unit counts are categorized as 'Demolitions' and subtracted from the inventory to calculate net change. The annual net housing unit estimates are summarized by county, jurisdiction, and census tract. The starting year in the time series will vary by county due to base year datasets differing from county to county. The time series for each county is as follows: King County: 2010-2024 Kitsap County: 2010-2024 Pierce County: 2012-2024 Snohomish County: 2011-2024 A new time series will be processed and published each year. Please note the estimates may shift from version to version due to updates in the data inputs and methodology refinements. Group Quarter Facilities are omitted from the final estimates. Unit counts for Mobile Home Parks are held constant except when an existing park is closed or redeveloped or a new park is opened. The 'Single-Family Attached' structure type category is defined in each county by the following: King: 'Townhouse Plat' present use category in the parcel table Kitsap: House type code '146 Townhouse' in the dwellings table Pierce: Built-As IDs 61, 65, and 68 in the improvements built-as table Snohomish: Property Class Codes 116 and 142 in the master table Missing Unit/Building Counts Housing unit and building counts are not available in the Snohomish County assessor datasets. Unit counts for single family parcels were assumed to = 1. Unit counts for multi-family parcels were populated by using utility hookup counts from the Snohomish County Public Utilities District (PUD). Building counts were populated by using a mix of utility customer property data and structure type information. Kitsap: Unit counts are accessed through a supplemental data request to the Kitsap County Department of Community DevelopmentPSRC 采用金县（King）、基萨普县（Kitsap）、皮尔斯县（Pierce）及斯诺霍米什县（Snohomish）的评估数据提取文件，对该时间序列内各年份的地块级住宅开发情况开展估算。本方法论通过识别住宅用途、单元数量、建筑数量的变量，结合建造年份变量，按建筑类型估算每年新增住宅单元。随后将最新版本的住宅评估记录与基准年数据集关联，以确定特定地块上的开发类型。本次追踪的开发活动类型包括：「新建开发（New Development）」、「再开发（Redevelopment）」与「重建/改造（Rebuild/Remodels）」。针对再开发与重建/改造场景，需将基准年的单元数量归类为「拆除（Demolitions）」并从库存中扣除，以此计算净变化量。年度住宅单元净估算值将按县、管辖区及人口普查区域（Census Tract）进行汇总统计。由于各郡的基准年数据集存在差异，该时间序列的起始年份因郡而异。各郡的时间序列范围如下： 金县：2010-2024年 基萨普县：2010-2024年 皮尔斯县：2012-2024年 斯诺霍米什县：2011-2024年 每年均会处理并发布新的时间序列数据集。请注意，由于数据输入更新及方法论优化，各版本的估算结果可能存在变动。集体宿舍设施（Group Quarter Facilities）未纳入最终估算结果。移动住宅公园（Mobile Home Parks）的单元数量保持恒定，仅当现有公园关闭、再开发或新建公园开放时方可调整。「联排独栋住宅（Single-Family Attached）」建筑类型类别在各郡的定义如下： 金县：地块表中的「Townhouse Plat」当前使用类别 基萨普县：住宅表中的房屋类型代码「146 Townhouse」 皮尔斯县：建筑属性Built-As表中的标识ID 61、65及68 斯诺霍米什县：主表中的物业类别代码116与142 缺失的单元/建筑数量说明： 斯诺霍米什县的评估数据集中未提供住宅单元与建筑数量。其中，独栋住宅地块的单元数量假设为1；多户住宅地块的单元数量通过斯诺霍米什县公共事业区（Public Utilities District, PUD）的公用设施接驳数量进行填充。建筑数量则结合公用事业客户物业数据与建筑类型信息完成填充。基萨普县：单元数量通过向基萨普县社区发展部提交补充数据请求获取。