ACS Housing Units by Year Built Variables - Tract

This layer shows housing units by year built by tenure (owner or renter). This is shown by tract, county, and state boundaries. This service is updated annually to contain the most currently released American Community Survey (ACS) 5-year data, and contains estimates and margins of error. There are also additional calculated attributes related to this topic, which can be mapped or used within analysis. This layer is modified every few years to change the top-end and bottom-end categories of the years. This layer is symbolized to show the predominant period that housing units were built in. To see the full list of attributes available in this service, go to the "Data" tab, and choose "Fields" at the top right. Current Vintage: 2015-2019 ACS Table(s): B25034, B25036, B25035, B25037 (Not all lines of ACS table B25036 are available in this layer.) Data downloaded from: Census Bureau's API for American Community Survey Date of API call: December 11, 2020 National Figures: data.census.gov The United States Census Bureau's American Community Survey (ACS): About the Survey Geography & ACS Technical Documentation News & Updates This ready-to-use layer can be used within ArcGIS Pro, ArcGIS Online, its configurable apps, dashboards, Story Maps, custom apps, and mobile apps. Data can also be exported for offline workflows. For more information about ACS layers, visit the FAQ. Please cite the Census and ACS when using this data. Data Note from the Census: Data are based on a sample and are subject to sampling variability. The degree of uncertainty for an estimate arising from sampling variability is represented through the use of a margin of error. The value shown here is the 90 percent margin of error. The margin of error can be interpreted as providing a 90 percent probability that the interval defined by the estimate minus the margin of error and the estimate plus the margin of error (the lower and upper confidence bounds) contains the true value. In addition to sampling variability, the ACS estimates are subject to nonsampling error (for a discussion of nonsampling variability, see Accuracy of the Data). The effect of nonsampling error is not represented in these tables. Data Processing Notes: This layer is updated automatically when the most current vintage of ACS data is released each year, usually in December. The layer always contains the latest available ACS 5-year estimates. It is updated annually within days of the Census Bureau's release schedule. Click here to learn more about ACS data releases. Boundaries come from the US Census TIGER geodatabases. Boundaries are updated at the same time as the data updates (annually), and the boundary vintage appropriately matches the data vintage as specified by the Census. These are Census boundaries with water and/or coastlines clipped for cartographic purposes. For census tracts, the water cutouts are derived from a subset of the 2010 AWATER (Area Water) boundaries offered by TIGER. For state and county boundaries, the water and coastlines are derived from the coastlines of the 500k TIGER Cartographic Boundary Shapefiles. The original AWATER and ALAND fields are still available as attributes within the data table (units are square meters). The States layer contains 52 records - all US states, Washington D.C., and Puerto Rico Census tracts with no population that occur in areas of water, such as oceans, are removed from this data service (Census Tracts beginning with 99). Percentages and derived counts, and associated margins of error, are calculated values (that can be identified by the "_calc_" stub in the field name), and abide by the specifications defined by the American Community Survey. Field alias names were created based on the Table Shells file available from the American Community Survey Summary File Documentation page. Negative values (e.g., -4444...) have been set to null, with the exception of -5555... which has been set to zero. These negative values exist in the raw API data to indicate the following situations: The margin of error column indicates that either no sample observations or too few sample observations were available to compute a standard error and thus the margin of error. A statistical test is not appropriate. Either no sample observations or too few sample observations were available to compute an estimate, or a ratio of medians cannot be calculated because one or both of the median estimates falls in the lowest interval or upper interval of an open-ended distribution. The median falls in the lowest interval of an open-ended distribution, or in the upper interval of an open-ended distribution. A statistical test is not appropriate. The estimate is controlled. A statistical test for sampling variability is not appropriate. The data for this geographic area cannot be displayed because the number of sample cases is too small.

本图层按照住房建造年份及保有状态（自有住房或租赁住房）展示住房单元数量，并以普查区（Tract）、县（County）及州（State）界为地理范围进行呈现。
本服务每年更新，以纳入最新发布的美国社区调查（American Community Survey，ACS）5年期数据，并包含估计值与误差边际。
此外还包含与该主题相关的衍生计算属性，可用于制图或分析工作。
本图层每数年更新一次，以调整建造年份区间的首尾分类。
本图层通过符号化展示住房单元的主要建造时段。
如需查看本服务中所有可用属性的完整列表，请前往"Data"选项卡，并点击右上角的"Fields"选项。
当前数据版本：2015-2019年ACS，涉及表格：B25034、B25036、B25035、B25037（本图层未包含ACS表格B25036的全部条目）。
数据来源：美国人口普查局美国社区调查API
API调用日期：2020年12月11日
全国统计数据：data.census.gov
美国人口普查局美国社区调查（ACS）：调查概况、地理与ACS技术文档、新闻与更新
本图层为即用型图层，可在ArcGIS Pro、ArcGIS Online、其可配置应用程序、仪表板、Story Maps、自定义应用程序及移动应用中使用。
数据亦可导出用于离线工作流程。
如需了解更多关于ACS图层的信息，请查阅常见问题解答（FAQ）。
使用本数据时，请注明引用美国人口普查局与ACS。

### 美国人口普查局数据说明
本数据基于抽样调查，存在抽样变异性。由抽样变异性导致的估计值不确定程度通过误差边际体现。本页展示的为90%置信度的误差边际。误差边际可理解为：估计值减去误差边际与估计值加上误差边际所构成的区间（即置信上下限）有90%的概率包含真实数值。除抽样变异性外，ACS估计值还存在非抽样误差（关于非抽样变异性的讨论，请参阅《数据准确性》一文）。本表格未体现非抽样误差的影响。

### 数据处理说明
本图层会在每年ACS最新数据版本发布时自动更新，通常为每年12月。本图层始终包含最新可用的ACS 5年期估计值，且会在美国人口普查局发布数据后的数日内完成年度更新。点击此处可了解更多ACS数据发布相关信息。
地理边界数据来源于美国人口普查局TIGER地理数据库。边界数据会与普查数据同步每年更新，且边界数据版本与普查局指定的普查数据版本完全匹配。本图层使用的普查边界已为制图需求裁剪掉水域及海岸线。其中，普查区的水域裁剪范围来源于TIGER提供的2010年AWATER（水域面积）边界子集；州与县边界的水域及海岸线则来源于50万比例尺TIGER制图边界Shapefile的海岸线数据。原始AWATER与ALAND字段仍作为属性保留在数据表中（单位：平方米）。
州图层共包含52条记录，涵盖美国所有州、华盛顿哥伦比亚特区及波多黎各。
本数据服务已移除位于海洋等水域区域、无人口的普查区（即编号以99开头的普查区）。
百分比与衍生计数及其对应的误差边际均为计算所得属性（可通过字段名中的"_calc_"后缀识别），且严格遵循ACS的相关规范。字段别名的命名依据美国社区调查汇总文件文档页面提供的表格框架文件生成。
部分负值（如-4444...）已被设置为空值，仅-5555...被设置为0。原始API数据中的这些负值用于标识以下情形：
1. 误差边际列对应的情形：无抽样观测值或抽样观测值过少，无法计算标准误及误差边际，不适合进行统计检验。
2. 无抽样观测值或抽样观测值过少，无法计算估计值；或由于其中一个或两个中位数估计值落在开放式分布的最低区间或最高区间，无法计算中位数比值。
3. 中位数落在开放式分布的最低区间或最高区间。
4. 不适合进行统计检验。
5. 估计值已被控制。
6. 不适合针对抽样变异性进行统计检验。
7. 由于抽样案例数量过少，无法展示该地理区域的数据。