The human loss from the coronavirus will not be reflected in the 2020 census because of a matter of timing, which could save a congressional seat for New York but cost Alabama one.

Because the start of the pandemic in the U.S. and the April 1 reference date used for the census fell so close to each other last year, the deaths that began in mid-March will not show up in the state population figures that determine political representation in Congress.

The timing will paper over the losses from the virus, which has killed around 44,000 people in New York state, including concentrations in some Ne...