1. A Model of Mass Incarceration and Crime
Peter Temin
MIT

2. Mass Incarceration US has the largest proportion of citizens in prison
Among advanced economies
US has 5% of world population and 25% of world prisoners
Mass incarceration is hardly mentioned in policy discussions
How many people know that 1 out of 3 African American men go to prison at today’s incarceration rates?
These are problems that urgently need to be addressed

3. Figure 1

4. Crime: c = f (i) Non-linear function
dc/di < 0 at low incarceration rates (i)
dc/di > 0 at high incarceration rates (i)
Todd Clear, Imprisoning Communities (2007)
Mass incarceration destroys community organization
Destroys “social capital”
See the movie, Moonlight
Leads to a cubic function (as Clear noted)

5. Incarceration i = g (c) / r
g (c) is linear for simplicity
Slope depends on public policies
The interest here is in changes in policies
The curves lead to a stable equilibrium as shown in Figure 2
As in other developed countries and the US before 1970

6. i c c i
Figure 2

7. American events America was in turmoil in the 1960s through the 1980s
Urban riots spread in the late 1960s
War on Drugs started by Nixon, expanded by Reagan
1986 and 1988 laws set minimum jail terms for drug crimes
Penalty for crack cocaine 100x penalty for powder cocaine
Blacks use crack cocaine; whites use powder
Sharply reduced the slope of g (c) as shown in figure 3 (line i3)
Created two stable equilibria
Line (i2) shows conditions during Nixon’s War on Drugs

8. i2 i1 c i3 c B A c i
Figure 3

9. Kerner Commission, 1968
Commission clearly stated that problems were societal
Riots were started by blacks trying for equality with whites
But Nixon created War on Drugs: crimes of individuals
He wanted to condemn blacks who opposed Vietnam War
He used individual crimes to demonize blacks
Nixon and Reagan followed Birth of a Nation: demonizing “rapists”
And KKK in lynching individuals
Creating a New Jim Crow (Alexander, 2010)
More history of state bills in my paper

10. What can be done now?
Obama tried to eliminate 100:1 punishment of blacks
2010 prison reform law only reduced it to 28:1
Private prisons now hold about 10% of prisoners
Private prisons want more—not fewer—prisoners
Larger share of immigrants who are waiting for hearings
Recommendations are to ease the burden of mass incarceration, not eliminate it
Educate prisoners, reduce employment discrimination, etc.
A few isolated hopeful signs
DAs (Krasner in Philadelphia) have declined to prosecute minor offenses
Federal FIRST STEP Act helps federal convicts (<10% of total)

11. Current prospects Staying at our new equilibrium for coming years
There are lots of DAs in lots of cities and states
The FIRST STEP Act is just that
Mass incarceration harms urban education
Children of felons cannot concentrate
Prisons receive state funds taken from education
New “originalist” judges probably will fight change
Taking us back to antebellum times
Current Incarceration rates by income and race (Chetty, 2018)

12. Incarceration Rates vs. Parent Income Rank Male Children
Pct. of Children Incarcerated on April 1, 2010 (Ages 27-32)
Incarceration Rates vs. Parent Income Rank Male Children
White Black 20 15
Diff. at p=25: -8.2 10
Diff. at p=75: -3.2 5 20 40 60 80
100
Parent Household Income Rank