Complex sentence: The Mayor's Office claimed that the detailed information provided for 549 census blocks is "nonsensical", listing examples of census data that show housing units located in the middle of a street that do not actually exist.
Split into simpler sentences: The mayor's office claims that the detailed information provided for 549 census blocks is "nonsensical". The District government cited examples of census data that show housing units located in the middle of a street that do not actually exist.