90.10—Form of formal challenge and time limit for filing.
The formal challenge shall be in writing and may be mailed or hand delivered to the Director, Bureau of the Census, Washington, D.C. 20233. The formal challenge shall include a list indicating the material submitted to the Chief, Population Division, during the informal stage, and shall include any additional relevant material it chooses to submit. The formal challenge shall be filed within 30 days of the date the State or unit of local government receives notification by certified mail (return receipt requested) of its right to proceed formally. If, however, a State or unit of local government has a sufficiently meritorious reason for not filing in a timely manner, the Bureau has the discretion to accept the formal challenge.