ACS Travel Time To Work Variables - Boundaries

Retirement Notice: This item is in mature support as of February 2026 and will retire in December 2027. A new version of this item is available for your use. Esri recommends updating your maps and apps to use the new version. This layer shows workers' place of residence by commute length. 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 symbolized to show the percentage of commuters whose commute is 90 minutes or more. To see the full list of attributes available in this service, go to the "Data" tab, and choose "Fields" at the top left. Vintage: 2019-2023 ACS Table(s): B08303 Data downloaded from: Census Bureau's API for American Community Survey Date of API call: December 12, 2024 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 and 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, specifically, the National Sub-State Geography Database (named tlgdb_(year)_a_us_substategeo.gdb). 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 erased for cartographic and mapping purposes. For census tracts, the water cutouts are derived from a subset of the 2020 Areal Hydrography boundaries offered by TIGER. Water bodies and rivers which are 50 million square meters or larger (mid to large sized water bodies) are erased from the tract level boundaries, as well as additional important features. For state and county boundaries, the water and coastlines are derived from the coastlines of the 2023 500k TIGER Cartographic Boundary Shapefiles. These are erased to more accurately portray the coastlines and Great Lakes. 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.

服务终止通知：本产品自2026年2月起进入成熟支持阶段，并将于2027年12月正式退役。目前已有新版本可供使用，Esri建议您尽快更新地图与应用，以采用新版本。
本图层以普查分区（census tract）、县及州界为边界，展示通勤时长对应的劳动者居住地分布。
本服务每年更新一次，纳入最新发布的美国社区调查（American Community Survey, ACS）5年周期数据，包含估算值与误差边际（margin of error）。此外还提供与该主题相关的额外计算属性，可用于制图或分析。
本图层的符号化设置用于展示通勤时长≥90分钟的通勤者占比。如需查看本服务中所有可用属性列表，请进入"数据"选项卡，并选择左上角的"字段"菜单。
数据年份：2019-2023年 ACS 表：B08303
数据来源：美国人口普查局美国社区调查（American Community Survey, ACS）API
API调用日期：2024年12月12日
全国统计数据来源：data.census.gov
美国人口普查局美国社区调查（ACS）：关于本次调查 | 地理与ACS技术文档 | 新闻与更新

本即用型图层可在ArcGIS Pro、ArcGIS Online及其可配置应用、仪表盘、Story Maps、自定义应用及移动应用中使用。数据还可导出用于离线工作流程。如需了解更多ACS图层相关信息，请访问常见问题解答（FAQ）页面。使用本数据时，请引用美国人口普查局与ACS相关成果。

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算值不确定程度，通过误差边际体现。此处展示的为90%置信水平的误差边际，其含义为：估算值减去误差边际与估算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估算值还存在非抽样误差（关于非抽样变异性的讨论，请参见《数据准确性》文档），本表格未体现非抽样误差的影响。

数据处理说明：本图层每年会在最新版ACS数据发布时自动更新，通常更新时间为12月。本图层始终包含最新可用的ACS 5年周期估算值，更新时间与美国人口普查局的发布计划基本同步，通常在其发布后数日内完成。点击此处可了解更多ACS数据发布相关信息。

边界数据来源：本图层的边界数据来自美国人口普查局TIGER地理数据库，具体为全国次州级地理数据库（命名格式为tlgdb_(年份)_a_us_substategeo.gdb）。边界数据与普查数据同步每年更新，且边界的年份版本与普查局指定的数据年份版本完全匹配。
为制图与地图绘制需求，本图层已去除普查边界中的水体及海岸线要素：
- 对于普查分区，水体裁剪范围源自TIGER提供的2020年区域水文边界子集，面积≥5000万平方米的大中型水体及其他重要地物已从分区边界中移除。
- 对于州和县界，水体及海岸线源自2023年500k分辨率TIGER制图边界形状文件，已完成裁剪以更精准地呈现海岸线与五大湖轮廓。
数据表格中仍保留原始的AWATER与ALAND字段，单位为平方米。
本州级图层共包含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。
本数据服务已移除水域区域（如海洋）内无人口的普查分区（即编号以99开头的普查分区）。

百分比、衍生计数及对应的误差边际均为计算所得值（可通过字段名中的"_calc_"前缀识别），且符合ACS的相关规范。字段别名名称源自ACS汇总文件文档页面提供的表壳文件。
部分负值（如-4444...）已被设置为空值，但-5555...除外，该值已被设置为0。原始API数据中的此类负值用于表示以下情形：
1. 误差边际列表明无足够抽样观测值可用于计算标准误差，进而无法计算误差边际，此时不适合进行统计检验。
2. 无足够抽样观测值可用于计算估算值，或无法计算中位数比率，原因是其中一个或两个中位数估算值落在开放式分布的最低区间或最高区间内。
3. 中位数落在开放式分布的最低区间或最高区间内。
4. 不适合进行统计检验。
5. 估算值受控制变量约束，不适合进行抽样变异性统计检验。
6. 由于抽样样本量过小，无法展示该地理区域的数据。