Mapping Inequality Redlining Areas

Visit Mapping Inequality for full details. History of this spatial data The majority of this dataset is derived from maps made by the Home Owners’ Loan Corporation (HOLC), a New Deal agency. Using data and evaluations gathered from local real estate professionals, HOLC created color-coded maps for more than 200 American cities. The maps used four colors to represent the “security,” or the determined relative riskiness of mortgage lending, for residential areas of each city. Green areas on the maps were called "A," "First Grade," or "Best" and were considered to be safest for loans. These areas were typically populated with wealthy, white residents that were born in the United States. Blue areas were called "B," "Second Grade," or "Still Desirable". Yellow areas were called "C," "Third Grade," or "Definitely Declining". Red areas were called "D," "Fourth Grade," or "Hazardous". HOLC recommended lenders "refuse to make loans in these areas [or] only on a conservative basis." These areas typically overlapped with Black and immigrant communities, which usually had lower incomes. These grades were a tool for redlining: making it difficult or impossible for people in certain areas to access mortgage financing and thus become homeowners. Redlining directed both public and private capital to native-born white families and away from African American and immigrant families. As homeownership was arguably the most significant means of intergenerational wealth building in the United States in the twentieth century, these redlining practices from eight decades ago had long-term effects in creating wealth inequalities that we still see today. This dataset also includes spatial data for more than 100 municipalities from redlining maps that were not made as part of HOLC’s City Survey Program. These places were typically smaller in size, falling below the population threshold of 40,000 that HOLC used to determine which cities they would survey. As these maps were not made as part of HOLC’s City Survey Program, the vast majority use different categories and colors than those used by HOLC. A new version of Mapping Inequality The University of Richmond Digital Scholarship Lab began the Mapping Inequality project in 2016. Using scanned images of HOLC City Survey maps, a team of students and scholars georeferenced the images and digitally traced their color-coded residential areas, creating a spatial dataset that has since been used in numerous studies and research projects. Over the course of the project, more cities and their maps were added, including redlining maps of smaller cities that were not a part of HOLC’s City Survey. Non-residential areas shown on the maps, such as industrial and commercial areas, were also traced and added to the spatial database. The spatial dataset has grown, and now contains 10,000 polygons that were created from maps of 328 cities in 43 states. Previous versions of this feature layer, which are missing cities and non-residential areas, are available here and here. Images of the redlining maps maps, and their derived data, as well as more in-depth reading on the history are available on the the Mapping Inequality website. The site also includes a searchable archive of the detailed area descriptions that accompanied redlining maps. These texts provide important nuance in the grades and are invaluable for laying bare the racist, nativist, and often anti-semitic prejudices underlying real estate practice and federal housing policy during the Great Depression. What's in this feature layer Each feature in this dataset is a polygon that represents an area that was drawn on a 1930s redlining map. They include the following fields: area_id (integer) is a unique identifier for each area. city (string) is the name of the city, town, county, etc. state (string) is the 2-letter U.S. Postal Service abbreviation for the state. city_survey (boolean, true=1, false=0) denotes whether the map was created as part of the HOLC City Survey Program or not. category (string) is the assigned category from a redlining map. On standard HOLC City Survey Program maps, the category values are “Best”, “Still Desirable”, “Declining”, or “Hazardous.” grade (string) is the letter grade used to grade the area. For non-residential areas and most cities that were not part of the City Survey, the value is null. label (string) is the label from a redlining map. For most HOLC City Survey Program maps, this value is a letter and number, which often corresponds to an area description viewable on the Mapping Inequality website. commercial (boolean, true=1, false=0) denotes whether or not an area is labeled explicitly as commercial or inferred to be commercial from a redlining map. industrial (boolean, true=1, false=0) denotes whether or not an area is labeled explicitly as industrial, or inferred to be industrial. residential (boolean, true=1, false=0) denotes whether or not an area is labeled explicitly as residential or inferred to be residential. fill (string) is a hexadecimal color code for symbology. The value is typically an approximation of the color shown on a redlining map. You can use this attribute field as a feature symbology in ArcGIS Pro. This spatial dataset is available in geojson and geopackage format on the Mapping Inequality downloads page. Images of the scanned redlining maps, including in spatially referenced geotiff format are also available. Updates March 1st, 2024 Fixed category errors on areas in Hudson County, NJ Added missing areas to Mt. Morris, MI (inset of Flint MI)请访问不平等测绘（Mapping Inequality）项目以获取完整细节。 ### 本空间数据的历史沿革 本数据集的大部分内容源自房主贷款公司（Home Owners’ Loan Corporation, HOLC）——罗斯福新政（New Deal）时期的联邦机构——所绘制的分级配色地图。HOLC依托从当地房地产从业者处收集的数据与评估结论，为全美200余座城市制作了专项地图，以四种色彩标注各城市居住区抵押贷款的“安全性”，即相对风险等级。 地图上的绿色区域被标记为“A级”“一级”或“最佳”，被认为是贷款风险最低的区域，通常居住着富裕的本土白人居民。蓝色区域为“B级”“二级”或“仍属宜居”；黄色区域为“C级”“三级”或“明显衰退”；红色区域为“D级”“四级”或“高风险”。HOLC建议贷款机构“拒绝向这些区域发放贷款，或仅以保守条款提供融资”。此类区域往往与黑人和移民社区高度重叠，而这类群体的收入水平普遍较低。 上述分级机制正是红线政策（redlining）的核心工具：该政策使得特定区域的居民难以甚至无法获得抵押贷款，进而难以实现住房自有。红线政策将公共与私人资本导向本土白人家庭，而非非裔与移民家庭。在20世纪的美国，住房自有权堪称代际财富积累的最核心途径，因此八十年前的红线政策所催生的财富不平等影响深远，直至今日仍清晰可见。 本数据集还包含了100余座非由HOLC城市调查项目制作的红线地图的空间数据。这些地区通常规模更小，人口未达到HOLC划定的40000人口调查门槛。由于这类地图并非HOLC城市调查项目的官方产物，绝大多数采用了与HOLC标准不同的分类体系与配色方案。 ### 新版不平等测绘（Mapping Inequality）项目 里士满大学数字学术实验室（University of Richmond Digital Scholarship Lab）于2016年启动了不平等测绘（Mapping Inequality）项目。团队利用HOLC城市调查地图的扫描件，组织学生与学者对图像进行地理配准（georeferenced），并数字化描记了其中的配色居住区，由此创建的空间数据集已被广泛应用于各类学术研究与项目。随着项目推进，团队新增了更多城市及其地图，包括未纳入HOLC城市调查的小型城市的红线地图。地图上标注的非居住区，如工业区与商业区，也被描记并加入空间数据库。 该空间数据集已扩充至包含来自43个州的328座城市的地图所生成的10000个多边形要素（polygon）。此前的要素图层版本因缺少部分城市与非居住区数据，可通过此处及此处获取。 红线地图的扫描图像、衍生数据，以及更深入的历史解读材料，均可在不平等测绘（Mapping Inequality）官方网站获取。该网站还设有可检索的存档库，收录了伴随红线地图的详细区域描述文本。这些文本为分级标准提供了重要的细节补充，也为揭露大萧条时期房地产行业与联邦住房政策中潜藏的种族主义、本土主义及反犹偏见提供了宝贵依据。 ### 本要素图层的字段说明 本要素图层中的每个要素均为代表1930年代红线地图上划定区域的多边形。其包含以下字段： 1. `area_id`（整数型）：每个区域的唯一标识符 2. `city`（字符串型）：城市、城镇、郡县等的行政区域名称 3. `state`（字符串型）：美国邮政管理局（U.S. Postal Service）规定的2位州缩写代码 4. `city_survey`（布尔型，`true=1`，`false=0`）：标识该地图是否属于HOLC城市调查项目的官方产物 5. `category`（字符串型）：红线地图分配的分类标签。标准HOLC城市调查地图的分类值为“最佳”“仍属宜居”“衰退”或“高风险” 6. `grade`（字符串型）：用于标注区域的字母等级。对于非居住区以及绝大多数未纳入城市调查的城市，该字段值为空 7. `label`（字符串型）：红线地图上的原始标签。对于大多数HOLC城市调查地图，该值通常为字母加数字组合，可在不平等测绘（Mapping Inequality）网站上查询对应的区域详细描述 8. `commercial`（布尔型，`true=1`，`false=0`）：标识该区域是否被明确标注为商业区，或经推断属于商业区 9. `industrial`（布尔型，`true=1`，`false=0`）：标识该区域是否被明确标注为工业区，或经推断属于工业区 10. `residential`（布尔型，`true=1`，`false=0`）：标识该区域是否被明确标注为居住区，或经推断属于居住区 11. `fill`（字符串型）：用于符号化显示的十六进制颜色码（hexadecimal color code），通常近似于红线地图上的原始颜色。可在ArcGIS Pro中将该属性字段用作要素符号化依据。 ### 数据获取方式 本空间数据集可在不平等测绘（Mapping Inequality）下载页面以GeoJSON与GeoPackage格式获取。带空间参考的GeoTIFF格式红线扫描地图图像也可在此处获取。 ### 2024年3月1日更新 1. 修正了新泽西州哈德逊县区域的分类错误 2. 为密歇根州芒特莫里斯（密歇根州弗林特市插图区域）补充了缺失的区域要素