COVID-19 was detected in Michigan two days after health officials found it in Ohio.

But now, more than a month into each state’s local epidemic, the differences are vast.

At least 1,921 Michiganders have died from COVID-19, the respiratory disease caused by the new coronavirus, compared to 361 Ohioans, as of Wednesday. Michigan’s first reported death? March 19. Ohio’s? March 20.

But now, experts believe Ohio’s epidemic to be comparatively under control, while in Michigan, CNN reports a Detroit hospital has become so overwhelmed that at least two people have died in its emergency room hallways.

More than 28,000 people in Michigan (population 9.9 million) have been infected, compared to about 7,600 people in Ohio (population 11.7 million).

In two bordering states of similar size on the same timeline, the question lingers: why do the two epidemics break so sharply?

“What you’re seeing in [Ohio’s] graph is essentially the ‘flatten the curve’ playing out in real time,” said Jordan Nelson, an epidemiologist at a hospital in Ohio (he asked that the hospital not be named).

The University of Washington’s Institute for Health Metrics and Evaluation, which produces state-by-state projections of caseloads and deaths, estimates 482 Ohioans will die of COVID-19 by August 4, compared to 2,373 Michiganders.

The model factors in three key government-mandated social distancing measures: stay-at-home orders, the closure of educational facilities, and the closure of non-essential services. In each category, authorities in both states implemented the changes within one day of one another.

In interviews, epidemiologists suggested race and class differences between the states are driving the divide, not the leaders at the top.

“The nature of who’s exposed leads a glide path into our poorest and our most marginalized communities,” said Abdul El-Sayed, an epidemiologist and former director of the Detroit Health Department. “There was this notion early on that this was the great equalizer. It’s definitely not.”

As proof, he pointed to the racial makeup of COVID-19 cases. In both Ohio and Michigan, black people are over-represented within the infected population.

In Ohio, black people comprise 21% of known cases and 27 percent of hospitalizations but about 13% of the state’s population . (About 17% of cases are of unknown race.)

In Michigan, black people comprise 33% of cases and 40% of deaths but about 14% of the state’s population . (Race is unknown in 29% of cases and 15% of deaths.)

“A lot of folks in low income, urban communities, are forced to go out to earn a paycheck,” El-Sayed said. “They’re forced to choose between staying in to save their lives or going out to earn their livelihood.”

Michigan’s outbreak centers on Detroit, in Wayne County, and surrounding areas.

It’s no coincidence, says Shawnita Sealy-Jefferson, that Detroit especially is feeling the crush of the virus. The city, population 673,000, is about 79% black, and known as one of the most segregated American cities.

Sealy-Jefferson, an epidemiologist at Ohio State University and Detroit native, said race undergirds the whole outbreak. For instance, the coronavirus is especially dangerous for people with preexisting conditions. She said black people are much more likely to have underlying health conditions while lacking access to quality health care.

A recent Pew survey found black people are far more likely to know someone who has been hospitalized or died from COVID-19 than white people or Hispanics.

“The impact that coronavirus is having in the city of Detroit, given the racial makeup of the city and given the history of racism in the city, systematic, institutional and structural, is not surprising to those of us who have been doing this work,” Sealy-Jefferson said.

There are other differences at play. Michigan hosted a primary election March 10, and a blitz of crowded rallies filled with staff bouncing from state to state and door to door. However, the epidemiologists agreed there’s no certainty what role that played in the current situation.

About 90,000 Michiganders have been tested, compared to 71,000 Ohioans.

However, Ohio, unlike Michigan, tracks hospitalization data. This gives state epidemiologists a better view of the virus’ spread.

“Epidemiology is the art of disease detective work, Nelson said. “Following diseases as they course through populations. Not having access to data showing where those cases are occurring is definitely not ideal for tracking the disease.”

As of Wednesday evening, about 28,000 Americans have died from COVID-19 of the roughly 633,000 diagnosed, according to data from Johns Hopkins University.

Data used in this story come from the Ohio Department of Health, the Michigan Department of Health, and the COVID Tracking Project.