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Research Report

The Impact of Census Timeline Changes on the Next Round of Redistricting

Summary: States must adapt to the new census data release schedule and adjust redistricting deadlines accordingly. Otherwise, courts may step in and draw their new congressional and legislative district boundaries for them

Census form

All states redraw their legislative and congressional districts every 10 years to comply with the constitutional mandate that districts be equally populated. States draw these districts using block-level data from the census conducted every decade. Under normal circumstances, states would have received this data by March 31, 2021.

However, the Covid-19 emergency forced the U.S. Department of Commerce and the U.S. Census Bureau to alter census field operations and data-processing protocols, resulting in a delayed timeline for releasing data. footnote1_h8iq2i1 1 Ron Jarmin, “2020 Census Processing Updates,” Director’s Blog (U.S. Census Bureau), February 2, 2021, On February 12, 2021, the Census Bureau announced that it would release the state population totals used to apportion congressional seats around April 30, 2021; that it would make granular redistricting population data available to states in a disaggregated and untabulated legacy format by mid-to-late August 2021; footnote2_hj739h6 2 “U.S. Census Bureau Statement on Release of Legacy Format Summary Redistricting Data File,” U.S. Census Bureau press release, March 15, 2021, and that states could expect final data delivery by September 30, 2021. footnote3_rp02iuj 3 James Whitehorne, “Timeline for Releasing Redistricting Data,” Random Samplings (U.S. Census Bureau), U.S. Census Bureau, last modified February 12, 2021,

The Commerce Department and the Census Bureau have said that this timeline is necessary to ensure high-quality data suitable for redistricting and other uses. While necessary, these changes will affect the legal or customary redistricting timelines of most states. In many, it will also require changes to deadlines and processes set by state law. As a result, states may need to adjust candidate filing periods and/or move primary election dates.

The new census schedule will not absolve states of their constitutional obligation to redistrict once new census data becomes available, even if they can no longer meet intended deadlines. footnote4_f43k9y5 4 Once census data is released, even if it is in September 2021, a constitutional obligation will be triggered because states will then have numbers showing that districts are malapportioned (i.e., not equally populated). If states do not make the adjustments necessary to complete redistricting in a timely fashion, courts will then need to step in and draw temporary maps to ensure that legally compliant districts are in place for upcoming elections — a power they have used in the past. footnote5_b9kkwwo 5 If states do not redistrict in a timely fashion, then individuals who suffer representational harms can ask a federal or state court to redraw districts to ensure that districts are equally populated and comply with other state and federal law requirements, including the Voting Rights Act. It is not uncommon for courts to draw maps because states fail to redistrict. Last decade, for example, courts drew maps in Colorado, Minnesota, New York, and Texas, among other states.

This memorandum examines

  • state-law deadlines for redrawing congressional and legislative district boundaries that will need to change to accommodate the later delivery of redistricting data, and
  • the potential impact on upcoming state and federal elections.

Changes to the Data Delivery Schedule

Under current law, the Commerce Department must provide two types of data used in redistricting after each census. The law also sets out timelines for the department to complete its data deliveries.

First, the Commerce Department must deliver apportionment counts to the president, setting forth the total population of each state and the number of congressional seats to which each state is entitled. footnote6_8wh4c9f 6 13 U.S.C. § 141(b). Under statute, the delivery date for this data was December 31, 2020. footnote7_66041ec 7 2 U.S.C. § 2a(a-b). The president then must transmit the apportionment counts to Congress, which is responsible for transmitting the apportionment counts to the governor of each state. The governing statute contemplated this process being complete by January 25, 2021. Id.

Second, the Commerce Department must provide states with the block-level population and demographic data needed to redraw congressional and legislative districts (commonly known in redistricting parlance as the P.L. 94–171 file, or simply the P.L. file). By statute, the Commerce Department was to provide each state with this information by April 1, 2021. footnote8_2r98jo5 8 13 U.S.C. § 141(c). In past decades, the Census Bureau distributed the information to states on a rolling basis, starting in mid-February of years ending in one; states with earlier redistricting deadlines received data first.

The Census Bureau has indicated that it expects to provide the president with apportionment counts by April 30, 2021; to make untabulated redistricting data (that states with the necessary technical ability could aggregate into a proper format) by August 16, 2021; footnote9_scil63i 9 The Census Bureau has not typically distributed raw data during past censuses. and to deliver P.L. files to the states by September 30, 2021, in a single national delivery rather than on a rolling basis.

One brief note: this analysis uses the September 30, 2021, date to assess state deadlines because it is unclear whether states will be able and willing to format the raw data made available in August 2021.

The Impact of Changes to the Data Delivery Schedule

Changes to the schedule for delivering redistricting data to states will require states to adjust their redistricting timelines to avoid having to use court-drawn maps for upcoming elections. Some states have already made the necessary accommodations; others are still in the process of doing so. This analysis reflects only conclusive changes made by states as of April 16, 2021. Any subsequent adjustments are not reflected.

Necessary changes may extend beyond redistricting deadlines. Some states may also have to adjust their candidate filing or qualification periods and/or move primary dates to have extra time to complete map-drawing. General elections will also be affected in the two states with odd-year elections.

In addition to redistricting deadlines, 10 states have fixed statutory or constitutional deadlines for public input or participation in the redistricting process that will be affected by changes to the redistricting data delivery schedule.

Part I provides a summary of the changes needed. Part II provides state-specific information.

End Notes