An Associated Press analysis finds that Detroit tops the list of cities that will be hardest to count in the 2020 census.
The Motor City has tens of thousands of vacant houses, sparse internet access and high poverty -- all factors that will present obstacles for an accurate tally.
Other Rust Belt towns that have lost population and Sun Belt cities with large numbers of immigrants and transplants will pose similar challenges.
Nationwide, about a quarter of the population lives in hard-to-count neighborhoods. The national headcount determines how federal money is spent and how many seats states get in Congress.