My title is "data scientist", and my main job function has been researching homicide and developing policies that reduce the homicide rate/increase the homicide clearance rate. I was embedded in the homicide unit of the Bureau of Detectives my local (Chicago) police department for a year and a half, and over that time, I saw footage of hundreds and hundreds of homicides, and one remarkable thing about them (besides how horrible they are) is how racially segregated the victimization is.

Over 80% of people shot or killed in the city I've lived in for over a decade are Black, and over 80% of shootings or homicides occur in neighborhoods where 80+% of residents are Black. These observables forced me to ask "Why are Black people so disproportionately victimized by violent crime?" and "Why is housing so intensely segregated?". Looking into segregation, I found this problem isn't unique to Chicago, rather it's a feature of every US city with a significant Black population [0], so the cause likely wasn't purely local in nature.

Growing up in the Detroit suburb I mentioned previously, I was very familiar with "redlining", as the the boundary line separating Detroit and Grosse Pointe was also the boundary line separating white and Black residents as that Wikipedia image clearly shows. I am somewhat embarrassed that I had to watch hundreds of people be murdered before I thought to ask "why are we still so racially segregated, over 50 years after LBJ's administration signed so many civil rights bills into law?" but asking that question lead me to investigate, and unsurprisingly, a nation-wide effect was the consequence of a nation-wide federal policy. The Federal Housing Administration's explicitly racist mortgage underwriting guidelines [1] explicitly incentivized racially segregating Black Americans out of areas with desirable land, low pollution, good schools, or good services. Here are some excerpts from this Federal policy that provided a massive investment vehicle nearly exclusively to white Americans:

* "Natural or artificially established barriers will prove effective in protecting a neighborhood and the locations within it from adverse influences. Usually the protection from adverse influences afforded by these means includes prevention of the infiltration of business and industrial uses, lower class occupancy, and inharmonious racial groups." (Section 935: "Natural Physical Protection"),

* "Areas surrounding a location are investigated to determine whether incompatible
racial and social groups are present, for the purpose of making a prediction regarding the probability of the location being invaded by such groups. If a neighborhood is to retain stability, it is necessary that properties shall continue to be occupied by the same social and racial classes. A change in social or racial occupancy generally contributes to instability and a decline in values." (Section 937: "Quality of Neighboring Development"),

* "However, if the children of people living in such an area are compelled to attend school where the majority or a considerable number of the pupils represent a far lower level of society or an incompatible racial element, the neighborhood under consideration will prove far less stable and desirable than if this condition did not exist." (section 951: "Quality and Accessibility of Schools"),

* "Satisfaction, contentment, and comfort result from association with persons of similar social attributes. Families enjoy social relationships with other families
whose education, abilities, mode of living, and racial characteristics are similar to their own." (Section 973: "Social Attractiveness"),

* "The infiltration of inharmonious racial groups will produce the same effects
as those which follow the introduction of incongruous land uses, when the latter tend to lower the level of land values and lessen the desirability of residential areas." (Section 1360, "Estimation of Remaining Physical and Economic Life of Buildings",

* "Racial Occupancy Desiqnation. This will be a letter indicating predominating racial characteristics, as follows: W-White M-Mixed F-Foreign N-Negro" (Section 1850)

* etc.

The FHA is a federal agency of the US government, which extends its reach across the US. The FHA's underwriting manual provided explicitly racist rules for determining whether the FHA would insure mortgages in an area, and if the FHA wouldn't insure mortgages in an area, that drastically reduced the number of banks that would issue mortgages in an area, which reduces the supply of buyers, which reduces land value. As a consequence, these policies incentivized real estate agents, banks, and white residents to push Black people out of desirable areas and into ghettos or areas far from economic opportunity. While these policies were outlawed by the Fair Housing Act of 1968, many millions of white Americans were able to buy real estate thanks to this program thereby enabling those white Americans to generate generational wealth on those assets, while Black Americans were denied access to this class investment, or could only access it through predatory means (eg "contract buying", where the buyer gains no equity until the very last payment is made, so failure to pay the penultimate payment could result in the resident being evicted with nothing). Even with redlining being explicitly illegal, banks still do it [2].

Over the past hundred years in the US, real estate has been an incredibly well performing investment, and access to this investment class many decades ago has allowed white families to profit from (and pass down) the compounding returns, while Black families were locked out of this. The resulting racial wealth gap [3] is staggering, with the median white family net wealth being around $188k, while the median Black family's net wealth is around $24k. As a result, segregation is maintained by the massive population of white Americans who are able to afford rents or mortgages in areas with high quality services, while the population of Black Americans able to afford the same rents or mortgages is disproportionately smaller.

As a result of this intense, systemic racial bias (which is undeniably obvious, just look at these maps [0]!), average Black Americans enjoy nowhere near the freedom that average white Americans do. Last year, there were over 4000 shootings and 769 homicides in Chicago, and the overwhelming majority of them occurred in the neighborhoods where the majority of Chicago's ~780,000 Black residents live. In the Detroit suburb I grew up in, I could (and regularly did) go for walks between midnight and 3am, never once thinking "oh, this isn't safe". None of my classmates were ever murdered or shot. Few if any of my classmates had to work a job to help their family get by, and even most of the mediocre students in my grade went to college. The conditions for Black people my age who just lived 4 blocks north of me, just across the Detroit border, lived under very different conditions.

If you think this is a "very small amount of racial bias", I assume you've just never taken the time to think about this issue. When you look a maps of racial segregation in the US [0], [systemic racial segregation via federal housing policy] is the only explanation that stands up to scrutiny. If you're actually interested in the truth on this issue, you should read "The Color of Law" [4]. If you aren't interested in the truth, keep doing what you're doing.

[0] https://www.washingtonpost.com/graphics/2018/national/segreg...

[1] https://www.huduser.gov/portal/sites/default/files/pdf/Feder...

[2] https://www.bloomberg.com/news/articles/2015-09-28/eight-rec...

[3] https://www.federalreserve.gov/econres/notes/feds-notes/disp...

[4] https://www.epi.org/publication/the-color-of-law-a-forgotten...