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Analyzing Montana’s Adjusted Redistricting Data

Used for state legislative redistricting

Full Report

The expanded report provides a detailed breakdown of the PL 94-171 data as released by the Census Bureau, compared to the reallocated, or adjusted data, provided by the state’s official redistricting body.

Specifically, this report details the differences in total population by census block, block group, tract, county, and state before and after reallocation. In states where comparisons are possible, these population differences are broken down by race and ethnicity.

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Overview

Montana uses adjusted (or modified) data for state legislative redistricting

  • 1,084,225 total population in the original PL file
  • 1,082,717 total population in the adjusted PL file
  • -1,508 total population difference between the two

Even in states where the total population is unchanged, the distribution of the population within the state can be affected.

To give you a sense for how these population shifts affect Montana’s redistricting, the average district sizes in Montana are:

  • 10,827 people per state House district
  • 21,654 people per state Senate district

The dataset used to create this report is the official redistricting dataset.

County Level Analysis

See the appendix for a detailed breakdown of county level population changes.

Montana's Adjusted Data Population Changes by County with Facility Locations

Block Level Analysis

In general, the changes in block population are not uniform: most blocks are unaffected by modification, while a handful of blocks lose a large amount of population that goes to a larger number of blocks in smaller quantities.

  • 88,417 census blocks in Montana
  • 87,336 census blocks have the same population following modification
  • 1,074 census blocks gained population following modification
  • 7 census blocks lost population following adjustment (Of the 7 census blocks that lost population following reallocation, 7 contained facilities according to our analysis conducted with PPI data.)
  • 0 census blocks have a negative population following modification.
Population Change Number of Blocks
Gained 100+ 0
Gained 51-100 0
Gained 11-50 0
Gained 6-10 5
Gained 1-5 1,069
No Change 87,336
Lost 1-5 0
Lost 6-10 0
Lost 11-50 1
Lost 51-100 1
Lost 100+ 5

Official Language

The official language for Montana’s adjustment is:

Inmate Reallocation DRAFT RFP — 12/10/21 meeting revisions

The commission seeks to adjust the Public Law 94-171 redistricting data (P. L. 94-171 data) to reallocate incarcerated individuals from the prison facilities in which they were held to their last known residence when possible. The adjusted data will be used when the commission draws state legislative districts in 2022 and at the start of 2023. The commission recognizes that Montana is limited in our ability to complete comprehensive inmate data reallocation, due to missing residential addresses for many incarcerated individuals. The Montana Department of Corrections currently does not collect last known residence information from inmates on intake into a prison facility. As a result, the residential address information in its offender management system is derived from any address information collected from individuals who have previously been under probation or parole supervision in the community and might be old or incomplete for the purposes of reallocation. The state also does not have residential address information for federal prisoners who were housed in facilities in Montana on Census Day.

The commission seeks an experienced technical contractor to complete the inmate data reallocation process by adjusting P. L. 94-171 data for Montana’s roughly 2,829 state inmates incarcerated in seven facilities on April 1, 2020, as well as the federal inmates. Roughly 1,132 inmates have residential addresses and the remaining do not have a last known address on file or have a previous prison facility listed as the last known address. Inmates without residential addresses and those with addresses that cannot be geocoded and reallocated to their smallest geographic unit will be excluded from the Census numbers that the commission will use to draw state legislative lines.

Appendix

Eight categories of race data were used, the total of these racial groups adds up to 100 percent.

  1. Non-Hispanic White
  2. Non-Hispanic Black plus Non-Hispanic Black and White
  3. Non-Hispanic Asian plus Non-Hispanic Asian and White
  4. Non-Hispanic American Indian plus Non-Hispanic American Indian and White
  5. Non-Hispanic Pacific Islander plus Non-Hispanic Pacific Islander and White
  6. Non-Hispanic Some Other Race plus Non-Hispanic Some Other Race and White
  7. Non-Hispanic Other multiple-race (where more than one minority race is listed)
  8. Hispanic
County Adjusted Population Diff. 1 White 2 Black 3 Asian 4 American Indian 5 Pacific Islander 6 Some Other Race 7 Other multiple-race 8 Hispanic
Lewis and Clark 159 87.4% 0.8% 1.4% 4.5% 0.2% 1.7% 0.3% 3.7%
Missoula 149 84.8% 1.1% 2.0% 4.8% 0.2% 1.6% 0.3% 5.1%
Silver Bow 100 88.5% 0.6% 1.0% 3.5% 0.2% 1.5% 0.1% 4.7%
Yellowstone 87 82.9% 1.3% 1.3% 6.2% 0.2% 1.4% 0.4% 6.1%
Flathead 81 89.5% 0.6% 1.3% 3.3% 0.2% 1.7% 0.2% 3.2%
Lake 57 65.4% 0.4% 0.8% 27.7% 0.1% 1.2% 0.5% 3.8%
Gallatin 51 87.4% 0.8% 2.1% 2.4% 0.1% 2.0% 0.2% 5.0%
Cascade 40 81.5% 2.0% 1.8% 7.6% 0.2% 1.6% 0.6% 4.8%
Hill 19 67.6% 0.6% 1.0% 25.9% 0.1% 1.1% 0.6% 3.1%
Lincoln 14 90.1% 0.5% 0.9% 3.7% 0.2% 1.6% 0.2% 2.9%
Ravalli 14 89.9% 0.5% 1.0% 2.8% 0.1% 2.0% 0.1% 3.6%
Deer Lodge 11 90.4% 0.4% 0.7% 4.4% 0.0% 1.1% 0.2% 2.8%
Fergus 11 92.3% 0.3% 0.7% 2.9% 0.0% 1.7% 0.1% 2.0%
Richland 10 86.1% 0.9% 1.4% 4.4% 0.1% 1.6% 0.3% 5.3%
Big Horn 9 26.0% 0.3% 0.5% 68.5% 0.1% 0.3% 0.5% 3.9%
Park 7 91.0% 0.6% 0.9% 2.9% 0.0% 1.5% 0.2% 3.0%
Rosebud 7 57.2% 0.3% 0.6% 37.6% 0.0% 0.7% 0.6% 2.8%
Glacier 7 25.4% 0.2% 0.4% 70.4% 0.2% 0.3% 0.9% 2.2%
Sanders 7 86.5% 0.4% 0.8% 6.8% 0.0% 2.4% 0.3% 2.8%
Stillwater 6 90.5% 0.3% 0.6% 2.7% 0.1% 2.6% 0.2% 3.0%
Broadwater 6 90.8% 0.7% 0.3% 3.0% 0.1% 2.0% 0.2% 3.0%
Blaine 6 41.8% 0.2% 0.4% 53.8% 0.0% 0.9% 0.6% 2.2%
Musselshell 6 90.4% 0.4% 0.5% 4.5% 0.1% 0.8% 0.2% 3.1%
Meagher 4 92.4% 0.8% 0.5% 1.9% 0.1% 1.1% 0.7% 2.4%
Beaverhead 4 88.9% 0.5% 0.6% 3.8% 0.1% 1.4% 0.1% 4.6%
Granite 3 92.7% 0.3% 0.1% 2.9% 0.0% 0.8% 0.6% 2.6%
Roosevelt 3 33.2% 0.5% 0.7% 62.3% 0.0% 0.6% 0.5% 2.2%
Carbon 3 91.7% 0.2% 0.6% 2.7% 0.2% 2.0% 0.2% 2.5%
Pondera 3 78.7% 0.4% 0.5% 17.6% 0.3% 0.7% 0.1% 1.6%
Valley 2 83.8% 0.4% 0.4% 11.6% 0.1% 0.9% 0.4% 2.3%
Chouteau 2 70.8% 0.4% 0.7% 24.2% 0.0% 0.9% 0.3% 2.7%
Teton 2 90.8% 0.8% 0.4% 4.6% 0.2% 1.6% 0.2% 1.4%
Fallon 2 93.7% 0.7% 0.3% 2.2% 0.2% 0.6% 0.3% 2.1%
Sweet Grass 2 90.6% 0.2% 0.7% 2.7% 0.1% 2.4% 0.6% 2.7%
Liberty 1 94.7% 0.4% 0.7% 1.7% 0.3% 1.1% 0.4% 0.7%
Madison 1 92.3% 0.2% 0.7% 2.2% 0.2% 1.5% 0.2% 2.8%
Wibaux 1 91.7% 0.3% 0.7% 0.7% 0.2% 1.9% 1.5% 2.9%
Judith Basin 1 93.1% 0.5% 0.4% 1.2% 0.1% 1.5% 0.7% 2.4%
Powder River 1 90.3% 0.4% 0.0% 4.8% 0.1% 2.1% 0.4% 2.1%
McCone 1 92.1% 0.2% 1.0% 2.4% 0.2% 1.8% 0.5% 1.9%
Mineral 1 89.2% 0.5% 0.9% 4.1% 0.1% 1.5% 0.5% 3.2%
Prairie 1 90.3% 0.2% 0.9% 3.6% 0.0% 0.8% 1.2% 3.0%
Garfield 1 95.9% 0.0% 0.2% 1.8% 0.1% 0.2% 0.7% 1.2%
Phillips 0 82.8% 0.2% 0.5% 11.4% 0.0% 1.8% 0.6% 2.7%
Wheatland 0 89.4% 0.5% 0.3% 3.4% 0.3% 2.4% 0.3% 3.3%
Treasure 0 90.3% 0.9% 0.4% 2.8% 0.1% 0.4% 1.0% 4.1%
Carter 0 94.8% 0.2% 0.7% 1.5% 0.1% 1.1% 0.9% 0.8%
Golden Valley 0 88.0% 1.0% 0.0% 2.3% 0.1% 3.6% 0.7% 4.3%
Sheridan 0 89.6% 0.8% 0.6% 4.5% 0.0% 1.3% 0.3% 3.0%
Petroleum 0 94.0% 1.0% 0.2% 2.2% 0.8% 0.0% 0.8% 1.0%
Daniels 0 88.3% 0.4% 1.4% 4.6% 0.1% 1.1% 1.2% 3.0%
Jefferson -16 90.4% 0.4% 0.9% 3.7% 0.1% 1.9% 0.2% 2.4%
Custer -54 90.2% 0.9% 1.0% 3.6% 0.2% 1.1% 0.1% 3.1%
Dawson -131 89.1% 0.8% 0.9% 4.0% 0.0% 1.7% 0.2% 3.2%
Toole -597 84.1% 0.8% 1.1% 9.3% 0.0% 1.0% 0.2% 3.6%
Powell -1,613 86.6% 1.4% 0.5% 7.8% 0.1% 1.0% 0.3% 2.3%