The spread of the coronavirus has ravaged businesses, closed schools, and wreaked havoc upon the lives of most people in the United States. But it is presenting a unique challenge to the Census Bureau.

Census officials have spent a decade planning for the coming months. Under the best of circumstances, it was always going to be a challenge to count hundreds of millions of people and to try and figure out where they lived as of Wednesday. But the spread of the coronavirus has added a really big hurdle.