The Ongoing Effects of Redlined Maps
Collecting and Mapping Data to Analyze the Impact of Redlining
What do you see when you walk around your neighborhood? What words would you use to describe it?
In the 1930s, real estate assessors walked around nearly 200 cities across the United States. They recorded what they saw. They used words and letters to assign ratings to neighborhoods. Then maps were created based on the ratings and data they recorded. The neighborhoods that rated the lowest, had red lines drawn around them. These areas became known as redlined neighborhoods.
Words matter
Assessors often used environmental words when rating neighborhoods. So, it begs the question: What were the environmental conditions of historically redlined neighborhoods, and what ongoing impacts do they have today?
The Digital Scholarship Lab at the University of Richmond analyzed the keywords in the assessors’ forms. They recorded data from primary source documents, like the example here, adding it into a database. The form's design requires information on environmental factors, demographics on inhabitants, and real estate history. Note how the inhabitants section makes room for the assessors to estimate the percentages of specific populations (race and nationality or "foreign-born") of the community.
Researchers then used Geographic Information Systems (GIS) to analyze the data. They found relationships between the environmental terms that were used, neighborhood ratings, redlined areas, and the current environmental conditions. Thanks to advances in technology, you can examine the environmental impact of redlining.
The results of the analysis show redlined areas in the cities, shown as red dots on the map, experience far more environmental issues such as:
- Urban heat islands, where some parts of a city experience higher temperatures than other parts, especially surrounding areas
- More impervious surfaces, such as roads or paved surfaces where water cannot be absorbed into the ground
- Lack of tree coverage, or areas where there are few or no shade trees
- Increased pollution, including increased exposure to hazardous air pollutants from traffic or factories
The ongoing social impacts of redlining include effects on home values, household income, intergenerational wealth-building, city services, education levels, crime, and health issues. These issues overwhelmingly negatively impact people of color.
So, why are some maps made in the 1930s still affecting U.S. cities and people today? To answer this, you must understand the complex relationship between the nation’s physical geography, social-historical context, and urbanization patterns.
Historical context
Slavery was abolished after the Civil War ended in 1865. By 1883, the Supreme Court heard the first racial segregation cases. By 1900, the coal-powered Second Industrial Revolution was in full swing, supported by railways that added over 150,000 miles of track. A massive influx of foreign immigrants soon followed.
By the 1920s, The Great Migration of Black Southerners seeking relief from Jim Crow laws fueled Northern urban growth. Yet, property restrictions in many Northern cities prevented many non-White people from buying homes.
By the 1930s, The Great Depression started, and Franklin Delano Roosevelt became president. He created several New Deal social aid relief programs. One of the programs was the Home Owners’ Loan Corporation (HOLC). The goal of the program was to prevent people from losing their homes by providing emergency, low-interest, long-term loans to over one million homeowners between 1933 and 1936, including to people of color and immigrants.
Drawing the lines
A HOLC map of Oakland, California, shows neighborhoods graded into four different categories.
In 1937, the HOLC hired real estate assessors to walk around neighborhoods and record data. They used environmental descriptions and recorded information related to features, for example, the locations of factories or parks. The forms also asked assessors to draw conclusions and assign a “trend of desirability” rating for each neighborhood based on their subjective perceptions. While the neighborhoods were assigned formal grades, sometimes assessors used terminology such as “best,” “desirable,” “declining,” or “hazardous,” for the grading scale. They assigned grades based on assumptions from their own experience and perceptions. Then, the color-coded grades were marked on maps.
These grades would be used to assign a residential security level, which mortgage lenders used to determine relative risk, meaning which areas were considered safe and a good investment. Because these grades were based on the biases built into the assessment process, they often divided neighborhoods along existing racial, ethnic, and socioeconomic lines. The grades include:
- Green = grade A. This grade was assigned to wealthy neighborhoods with predominantly white populations.
- Blue = grade B. HOLC assessors assigned this grade to places where predominantly white families with professional jobs lived.
- Yellow = grade C. These areas were usually home to working class people. HOLC assessors considered these areas as declining often because of growing communities of Black people or new immigrants.
- Red = grade D. HOLC assessors often called these areas “hazardous.” The neighborhoods tended to be industrial areas and home to low-income people who were predominantly part of Black and immigrant communities.
The Federal Housing Administration (FHA) was also created in the 1930s to help protect local banks against losses if borrowers couldn’t make payments. Evidence suggests that the FHA and banks used the HOLC maps when issuing loans. Often the FHA declined issuing insurance for loans in the lower-graded areas, mostly where people of color lived, and many banks would not grant loans that weren’t backed by the FHA.
Evidence also suggests that the Federal Housing Administration (FHA) and banks continued to use the HOLC maps long after the HOLC program ceased in the 1940s.
The grades were based on neighborhood descriptions, not the individual borrowers. While the maps that are available to view online didn’t create racism, they became a tool for upholding racist systems and policies.
Redlining and residential inequities have many complex social, economic, and environmental legacies. To better understand some of the environmental issues, explore the relationship between redlining, modern population trends, and factors such as temperature and air quality in St. Louis, Missouri, and Oakland, California.
Environmental legacy
Urban heat islands are areas where surface temperatures are higher than in surrounding areas. The causes of the higher temperatures may include higher amounts of impervious surfaces and fewer trees, factors that relate to urban design and land uses. They're most intense in formerly redlined neighborhoods that relate back to the HOLC classifications that were given in the 1930s.
A view of St. Louis, Missouri is shown from the Illinois side of the Mississippi River.
St. Louis, Missouri
The Redlining Basemap is shown.
Located on the western bank of the Mississippi River, St. Louis became a destination for many Black Americans during the early years of the Great Migration.
An aerial view shows the St. Louis riverfront and downtown St. Louis in the 1920s. Photo: Missouri Historical Society
Using satellite data, cartographers analyzed temperatures across neighborhoods in the city. They compared average temperatures of neighborhoods based on their 1930s HOLC-designations. The analysis shows that neighborhoods given a grade of A in the 1930s had cooler averages today than the neighborhoods with B, C, and D grades.
This is a map of the warmest and coolest parts of St. Louis and suburbs on July 18, 2019, and includes HOLC class labels.
This grade A neighborhood is one of the coolest areas. The relative temperature is related to the amount of tree coverage and vegetation.
In contrast, an area near the port, a grade D neighborhood, is one of the warmest. The temperature is related to the low amounts of vegetation and high proportion of paved surfaces. Paved surfaces also create higher flood risks, which is also common in redlined areas.
Effects of urban heat islands
Heat islands are defined by higher daytime and nighttime temperatures compared to surrounding areas. The impervious surfaces contribute to heat islands because pavement absorbs heat and has fewer trees, resulting in less shade. Pavement also prevents water from being absorbed into the ground, leading to flooding.
Heat islands have higher levels of air pollution, higher energy bills, more heat-related illness, chronic respiratory symptoms, and even pre-term birth. During summer months, St. Louis temperatures can reach well over 90 degrees Fahrenheit with high humidity. These conditions can lead to illness or even cause death.
2020 Economic Data by grouped by HOLC Designated Area
Recent demographic information shows the dramatic difference between residents of grade A neighborhoods and grade D neighborhoods today. Note the difference in the median home value, education, and median household income statistics.
Comparing the maps below, you can see how heat islands relate to the urban landscape and the historic HOLC zones. Observe the locations of city parks and their relative temperatures. Then explore areas that are more industrial—namely those along the Mississippi River where temperatures are relatively warmer.
You may notice a few patterns appear from the St. Louis heat analysis. Observe the warmer temperatures in the D areas that are on the river at the industrial port areas. Then look to the west of the D areas; the A neighborhoods are much cooler. This example is not average, though, since most areas next to rivers tend to be cooler because of tree canopy shade and soil along them.
As you can see, redlined areas in St. Louis continue to experience the ongoing effects of historical labels in the flat land in Missouri. In contrast, by using GIS and 3D maps you can see how the relationship between the physical geography and how it affects humans in the hillside city of Oakland, California, experiences different environmental challenges related to redlining.
An aerial view shows the City of Oakland, California.
Oakland, California
The Redlining Basemap is shown.
The 1849 California Gold Rush caused Oakland’s population to grow rapidly. Its location on the coast and in the San Francisco Bay made Oakland an obvious pick for the western terminal for the Transcontinental Railroad. It’s also an ideal site for a shipping harbor and the fifth busiest seaport in the United States.
Photo: Library of Congress
Oakland’s port and rail hubs made it an industrial and manufacturing hub. During WWII, Oakland grew rapidly as Black Americans from the South sought out jobs in this booming sector. Racial tensions locally and nationally came to a head in Oakland around 1966. Urban renewal programs, widespread gentrification, and opposition to new housing have continued to fuel these tensions. The resulting inequality in the Bay Area is more apparent than ever.
Where the air is cleanest
The topography of the East Bay where Oakland sits starts as a flat plain near the water. Moving east, the slope steadily increases into the historically HOLC designated grade A neighborhoods along the foothills and ridges of Oakland and Berkeley. Explore the relationship between topography and the HOLC classes.
The city of Oakland, California, located on the eastern shore of San Francisco Bay.
The vertical terrain of Oakland outlines a stark economic divide between the more affluent hills communities and lower-income flatlanders.
In 1937, the HOLC assessors used phrases including “charming neighborhood,” “groves of trees,” and “good views” to describe the foothills and hills of the East Bay range–given A grades.
Meanwhile, they described flat areas along the bay shore using racial and ethnic descriptions and “odors from nearby industry.” These areas were given D grades.
With a 3D view of the data, we can compare each HOLC neighborhood by its average terrain slope, which resembles a set of bleachers that climb to the east. Now you can see the clear relationship between HOLC grade and elevation.
Wealthy people usually live in the more expensive areas. Something that may not be as obvious, though, is that lower-income people who live in the lower elevations have higher rates of emergency room visits caused by asthma, congestive heart failure, and stroke. The wealthier people on top of the hill also have life expectancies that are 14 years greater than someone in West Oakland, which is a neighborhood that was redlined in the 1930s.
2020 Economic Data by grouped by HOLC Designated Area
Recent demographic information shows the dramatic difference between residents of grade A neighborhoods and grade D neighborhoods. Observe the difference in the median home value and median household income.
Reasons for the health inequalities include pollution from truck diesel on the highways and from shipping vessels at the port interacting with the local climate. Oakland's physical geography can hold polluted air closer to the ground. Marine inversions happen when sea-level air cooled by the Pacific Ocean gets trapped under warmer and denser air from above. So, the hills end up keeping pollution at the bottom of the Oakland hills. Wealthier inhabitants in Oakland literally get a breath of fresher air.
What you can do
The GIS analysis shows the patterns in the publicly available data. Now that you are aware of the patterns you can use this same information to empower yourself to effect positive change in your community.
How can you make a difference? By attending your city's planning committee public meetings. Show up. Make your voice heard. Find out how and where funds will be spent and make suggestions to create new green spaces and parks. And ensure that your community members have fair representation to create a balanced society. Making change happen is possible when you take action.
Related reading
The story you are reading is an adapted and abbreviated version of The lines that shape our cities . Keep reading and doing advanced web searches for other ArcGIS StoryMaps to learn more about redlining and how it affects your community.
