Redistricting
Contents
P.L. 94-171 Redistricting Data
The U.S. Census Bureau plays a critical, but specific, role in the redistricting process. While the states are responsible for drawing their own electoral district boundaries, the Census Bureau provides the foundational data and a program to facilitate the process.
Breakdown of the Census Bureau's role:
A Legal Mandate: Public Law 94-171
The Bureau's involvement in redistricting is codified by Public Law 94-171, which was passed in 1975. This law mandates that the Census Bureau provides state governments with the detailed, small-area population counts they need to redraw their legislative districts.
Key requirements of the law include:
| • | Providing Data by April 1st: The Census Bureau must deliver the necessary data to the governor and legislative leaders of each state within one year of Census Day (April 1st of the decennial census year). |
| • | Nonpartisan Process: The Bureau is required to carry out this program in a nonpartisan manner. |
| • | State Participation: States have the opportunity to participate in a multi-phase program to ensure the census data is aligned with their specific geographic needs for redistricting. |
The Census Redistricting Data Program
To fulfill its legal obligation, the Census Bureau runs the Redistricting Data Program (RDP). This program involves several phases that take place before and after the decennial census:
| • | Phase 1: Block Boundary Suggestion Project (BBSP): States can suggest using non-traditional features like power lines or streams as census block boundaries, which helps create more meaningful districts that align with local electoral boundaries. |
| • | Phase 2: Voting District Project (VTDP): States can submit and verify their voting district boundaries (like precincts or wards) to the Census Bureau. This ensures that the population data is tabulated to these specific local areas. |
| • | Data Delivery: The Census Bureau provides the final redistricting data, also known as the "P.L. 94-171 Redistricting Data Summary File." This file contains detailed population counts for various geographic levels, from states down to individual census blocks. |
What Data is Provided?
The data delivered by the Census Bureau is highly specific and designed for the needs of redistricting. It includes:
| • | Population Counts: Totals for the entire population and for the population aged 18 and over. |
| • | Race and Ethnicity Data: Detailed breakdowns of population by race and Hispanic or Latino origin. |
| • | Housing Unit Counts: Information on the number of housing units and their occupancy status. |
| • | Group Quarters Population: Counts for populations in institutional and non-institutional group quarters (e.g., college dorms, prisons, nursing homes). |
Important Distinctions
It's crucial to understand what the Census Bureau does not do in this process:
| • | The Census Bureau does not draw the districts. That is the responsibility of state legislatures or, in some states, independent commissions. |
| • | The Census Bureau does not provide data on voter registration or political affiliation. The data is strictly nonpartisan and based on the enumeration of all residents, as mandated by the Constitution. |
| • | The data is based on the decennial census's full count. While the American Community Survey (ACS) provides ongoing demographic data, the P.L. 94-171 redistricting data is based on the full, once-a-decade count, which provides the most accurate and granular information at the census block level. |
In summary, the Census Bureau's role is to act as a data provider, giving states the essential, legally-mandated information they need to carry out their constitutional duty of redrawing electoral boundaries.