The group has urged the US Census Bureau to reconsider the proposal, which would add two new parts to the Code of Federal Regulations governing the decennial census.

The first proposal from the agency would see the regulation include an outline of the residence criteria used for identifying people’s ‘usual residence’, changing existing census residence criteria.

Secondly, the proposal would involve establishing standards and restrictions for the inclusion of certain demographic questions on the census questionnaire, which, according to The Census Project, would ‘remove’ race and ethnicity questions.

The Census Bureau is also proposing to define the ‘census enumeration period’ to run from 3^rd January 3 to 1^st April during decennial census years to determine usual residence, which would replace the traditional 1^st April census date.

The proposals are open for comment until 2^nd November. In written comments submitted by The Census Project, the group said the proposed rule “would unravel centuries of standard practices that have defined decennial census operations and undermine the quality and accuracy of its data.”

Census Project co-directors Mary Jo Mitchell and Howard Fienberg said: “Changes of this magnitude have the potential to drastically alter how the 2030 census is conducted as well as its outcome.”

The Census Project also expressed concern about the limited opportunity for public scrutiny, stating: “While we appreciate the extended comment period, it is still insufficient given the rule’s potential consequences.”

Research industry organisation The Insights Association said earlier in the year that dropping race and ethnicity questions from the census would  ‘hobble’ research. 

Additionally, a proposed bill that would amend the United States Code in relation to the census, if passed, could see the questionnaire include a citizenship question.