How NCSL and the Census Bureau Modernized Redistricting

How NCSL and the Census Bureau Modernized Redistricting

A partnership spanning more than 50 years created a collaborative process aligning census data and state redistricting needs.

The U.S. Census Bureau's headquarters building near Washington, D.C. (Courtesy Skidmore, Owings & Merrill)

Congress passed a landmark piece of legislation in 1975 fundamentally changing the decennial state redistricting process. Enacted that year as Public Law 94-171, or PL 94, the law required the U.S. Census Bureau to deliver small-area population data formatted in geographic units tailored to state needs for legislative redistricting within a year of the decennial census.

PL 94 marked a pivotal shift in the relationship between federal data collection and state redistricting. Once chaotic and inconsistent, redistricting was transformed into a more structured and collaborative practice. The bill emerged from years of efforts to align census data and state redistricting needs. Legislative staff, working through a reapportionment committee formed by the National Legislative Conference-one of three organizations that merged to form NCSL in 1975-helped lay the groundwork for PL 94 and other legislative reforms that revolutionized the redistricting process.

Former NCSL senior leader Karl Kurtz, who worked for the organization from its founding to his retirement in 2014, says the NLC committee's work on redistricting provided a vital example of how "collaborative and motivated legislators and legislative staff could have significant sway on an important federal-state relations issue."

One Person, One Vote, 50 States

The push for cooperation between states and the Census Bureau stemmed from the U.S. Supreme Court's 1964 Reynolds v. Sims decision, which established the "one-person, one-vote" principle, requiring districts to have roughly equal populations. The principle exposed widespread issues, including vast disparities in district composition in states that had not redistricted as their populations shifted over time. In some legislative chambers, districts with several hundred thousand people had the same representation as others with just over 10,000 residents. The need for timely, accurate census data became urgent, but the 1970 census data was delayed and largely unusable for redistricting.

Calls for reform grew louder and resulted in the introduction of legislation that would later become PL 94.

Fifty years of collaboration between the Census Bureau, the National Legislative Conference and later NCSL began in the House Subcommittee on Census and Statistics in the fall of 1973, with the census director, Vincent Barabba, opposing the bill and an Iowa legislative analyst, Phillip Burks, advocating for it on behalf of the NLC. The hearings underscored the core tension: States needed timely data, while the Census Bureau urged caution due to concerns about the cost and viability of administering the law.

Sponsors such as U.S. Rep. Harold Runnels (D-N.M.) argued that census data often arrived too late and misaligned with precinct boundaries. Barabba acknowledged past issues but warned that customizing data for 50 states could politicize the process. Despite the hearings becoming a debate over how far Congress should go in reshaping census operations, things seemed to be looking up for possible passage in 1974. Ultimately, the bill stalled in the wake of Watergate.

NCSL and PL 94

When Congress returned to the bill in 1975, the legislative landscape had changed. States, seeking more effective representation in Washington, recognized the need for stronger coordination among themselves and the organizations that represented them. This push culminated in the formation of NCSL through a merger of the National Legislative Conference, the leadership-focused National Conference of State Legislative Leaders and the policy-and-process-oriented National Society of State Legislators.

Having absorbed the NLC and its reapportionment committee, NCSL became the lead negotiator on behalf of state legislatures. The committee had been engaging with Census Bureau officials for years and had developed the technical expertise necessary to navigate redistricting data needs.

By 1975, the bureau was less resistant to the legislation, and the debate moved from whether to pass the bill to how to implement it without overwhelming the agency. A voluntary opt-in program emerged as a critical compromise, allowing states to submit redistricting geography in advance. This reassured skeptics, secured bipartisan support and narrowed the bill's scope to avoid broader political pitfalls.

With those conditions, the bureau dropped its opposition, agreeing it could meet the law's terms as long as participation remained optional and states submitted their data years in advance. The bill passed both chambers and President Gerald Ford signed it into law on Dec. 23, 1975, with little fanfare but lasting consequence.

NCSL celebrated the enactment of PL 94 as a victory for the former NLC reapportionment committee and for legislative staffers, including Iowa's Burks and New Jersey's Samuel Alito Sr., director of his state's Office of Legislative Services and the father of future Supreme Court Justice Samuel Alito Jr.

The senior Alito worked behind the scenes with the Census Bureau to bridge the gap between state data needs and federal capabilities. And the reapportionment committee's efforts transformed the bureau's work and greatly improved the redistricting process, Kurtz says. These contributions continue to shape state legislative redistricting today.

Andrew Flaxman was a 2025 legal intern in NCSL's Elections and Redistricting Program.