California Attorney General Xavier Becerra responded by filing a lawsuit against Commerce Secretary Wilbur Ross and the federal government.
Becerra made the official announcement Tuesday during a press conference calling the additional question unconstitutional.
"We are simply trying to convey a very simple message: we want everyone to count," said Becerra.
Given California's large immigrant population, Becerra believes the question would cause a massive undercount in many communities.
"Given the way this administration has attacked immigrants you can understand why immigrant families would be afraid to fill out the census questionnaire," said Becerra.
The Trump Administration believes the citizenship question would help enforce the voting rights act.
"We've contained this question that's provided data necessary for the Department of Justice to protect voters," said White House Spokesperson Sara Sanders.
Critics worry a population undercount would lead to a loss in federal funding, services, and maybe even congressional seats.
"The Trump Administration's decision last night rolls back the clock on civil rights and voting rights," said Becerra.