Hansi Lo Wang for NPR:

Under pressure from the Trump administration to deliver 2020 census results by the end of this year, the U.S. Census Bureau has set a cutoff date for receiving paper forms for the once-a-decade head count, NPR has learned.

The bureau confirms to NPR that it plans to only process paper census questionnaires postmarked by Sept. 30 — its new end date for all counting efforts — and received by Oct. 7 at one of its two data processing centers in Phoenix and Jeffersonville, Ind.

Although the vast majority of households (80%) that have filled out a census form on their own did so online, paper forms have been the second-most popular way for those households — about 1 in 5 — to get counted, especially in rural areas.

That’s why recent cuts to the U.S. Postal Service are raising concerns among census advocates. While much of the country’s attention has been on the potential impact on November’s election, some census watchers are worried that any delivery delays over the next few weeks could jeopardize the accuracy of census data collected from sparsely populated parts of the country.