Kevin Systrom, founder of Instagram, has been working on this site that gives up-to-date reads on Rt by state, giving a read on how fast the coronavirus is spreading.

These are up-to-date values for Rt, a key measure of how fast the virus is growing. It’s the average number of people who become infected by an infectious person. If Rt is above 1.0, the virus will spread quickly. When Rt is below 1.0, the virus will stop spreading.

Tabbing between the time ranges shows how infection rates are changing over the last 4 weeks.