The New Dynamics of Mass Incarceration
After decades of continuous and unified growth across all
states from the 1970s to the early 2000s, the landscape of U.S.
incarceration fragmented into distinct trends. The last decade
has been characterized as an era of reform, and nationwide
prison data does show a 24 percent drop in prison admissions.
But if the 10 states with the largest declines in prison
admissions are pulled out, data from the remaining 40 states
reveals a small but significant overall increase in admissions.
Moreover, incarceration rates and incarcerated populations can
be vastly different depending on both the locale and the lens
through which they are viewed. In this complex landscape, the
traditional approach of using state-level prison population as a
proxy for all incarceration is now too broad a brush with which
to paint the new dynamics of incarceration. In this report, the
Vera Institute of Justice (Vera) proposes a new way to consider
incarceration that will lead to a more comprehensive
understanding of its current state and how changes to one facet
can affect the entire system.
Vera proposes analyzing incarceration using a
comprehensive set of metrics and, in so doing, identifies four
distinct trends: decarceration, stagnation, jurisdictional shifts,
and continued growth. To aggregate and analyze these metrics,
Vera researchers merged two federally collected prison
datasets—the National Corrections Reporting Program and the
National Prisoner Statistics Program—with the jail data in
Vera’s Incarceration Trends data tool, sourced from the federal
Annual Survey of Jails and Census of Jails. In addition, Vera
researchers collected data on incarceration directly from states.

Overview
By observing the following four additional metrics in
combination with prison population, researchers and reformers
will be better able to craft systemic solutions that can lead to
true reform.
>> Jail admissions. The number of times people are sent
to local jails annually is the best, albeit rough,

June 2018
Fact Sheet

estimate of how many people are directly impacted by
local incarceration.
>> Pretrial jail population. The number of people held
in jail awaiting the resolution of their charges
provides a metric that is relatively easy to compare
across counties and states.
>> Sentenced jail population. The number of people
serving time in local jails helps represent the entirety of
the sentenced population, particularly as states shift
incarcerated populations between prisons and jails.
>> Prison admissions. The number of people admitted
to state prison in a given year presents a timely
indicator of changing prison usage.

Findings
Using these metrics, Vera researchers uncovered four trends
that show America is not in a period of universal decline in
incarceration, but that the nature of incarceration varies
from place to place in meaningful ways:
>> Decarceration. Large urban areas are decarcerating at
historic rates, driving overall statistics for states as
diverse as California, New York, and Missouri. These
urban shifts, however, have the potential to
statistically overwhelm concurrent incarceration
growth in adjacent rural areas and create a false
perception of overall decarceration in the state.
>> Stagnation. In some states, like Louisiana and Virginia,
each metric shows a relatively flat trend. But although
prison and jail incarceration rates have stopped growing
in these areas, they are still at or near all-time highs.
>> Jurisdictional shifts. In other states, jails are growing
while prisons shrink—or vice versa. For example,
while Indiana reported a 21.4 percent drop in prison

For more information
To read the full report, visit
www.vera.org/the-new-dynamics-of-mass-incarceration.
For more information about this report or the Incarceration
Trends project, contact Jacob Kang-Brown, senior research
associate, at jkangbrown@vera.org. For more information
about Vera’s work to reduce the use of jails, contact Nancy
Fishman, project director at Vera’s Center on Sentencing and
Corrections, at nfishman@vera.org.
The Vera Institute of Justice is a justice reform change agent.
Vera produces ideas, analysis, and research that inspire
change in the systems people rely upon for safety and justice,

and works in close partnership with government and civic
leaders to implement it. Vera is currently pursuing core priorities
of ending the misuse of jails, transforming conditions of
confinement, and ensuring that justice systems more effectively
serve America’s increasingly diverse communities. For more
information, visit www.vera.org.
This report was created with support from the John D. and
Catherine T. MacArthur Foundation as part of the Safety and
Justice Challenge, which seeks to reduce over-incarceration by
changing the way America thinks about and uses jails. More
information is available at www.SafetyandJusticeChallenge.org.
© 2018 Vera Institute of Justice. All rights reserved.

admissions in 2016, its jail admissions increased by 32
percent between 2015 and 2017. In Minneapolis,
Minnesota, in contrast, Hennepin County has
experienced a 20 percent jail incarceration rate drop
since 2007, while prison admissions grew by 50
percent over the same period. This trend suggests that
reform tactics may be merely driving populations
between different forms of incarceration rather than
leading to overall decarceration.

>> Growth. While growth has slowed in many parts of the
country, it is still the dominant dynamic in states like
Arkansas, Kentucky, Oklahoma, and West Virginia, which
continue to incarcerate people in both prisons and jails at
all-time high rates that keep increasing year after year.
Using these proposed more granular and comprehensive
metrics, researchers and reformers can better track the
interplay between jails and prisons in this new era, and craft
solutions that will truly unwind mass incarceration.

Figure 1
How many years until incarceration in the United States falls to 1970 rates?

State prison incarceration rate (per 100,000 working age residents)

 Measured

 Extrapolated

700

600

500

2166

1970
400

300

2017

200

0
1975

2000

2025

2050

2100

2075

2125

2150

2175

Note: This projection is based on the average annual rate of decline in the state prison incarceration rate since its
peak in 2007.

Figure 2

Diverging trends in prison admissions
10 states with the largest decline

Other states

Total

Prison admissions rate (per 100,000 working age residents)

400
350

1%

300

-24%

250

-48%

200
150
100
50
0
1980

1985

1990

1995

2000

2005

2010

2015

The 24 percent drop in the national prison admissions rate since 2006 is due entirely to a 48 percent drop in 10 states.

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