Updated April 29 with data through April 28. 

In geographic terms, the Corona Virus has become the Northeast Corridor Virus:  NE Corridor metros account for 6 of the 8 hardest hit large metros, and have 6 of the 8 highest rates of reported new cases per capita.

Among the 53 metro areas with a million or more population:

• New York, New Orleans, Detroit, Boston and Philadelphia have the highest incidence of pandemic among large metros.
• The number of new cases reported in the past day, per capita, is highest in Boston, New York, Philadelphia, Buffalo and Washington
• Chicago, Boston, Philadelphia, Providence, Washington and Hartford have higher than average incidence, and are experiencing faster than average growth in reported cases.  
• The typical (median) large metropolitan area had a rate of about 164 reported cases per 100,000
• Half of all metropolitan areas had between 101 and 279 reported cases per 100,000.
• The mean rate of increase in the number of cases in large metro areas has been about 3.5 percent per day in the past week.
• In previous commentaries, we’ve addressed the implications of the pandemic for cities: challenging a New York Times story suggesting that the pandemic will result in urban outmigration, exploring a very dense North American city that’s kept the pandemic at bay, and looking at the strong correlation between city and suburban incidence rates within metro areas.
• For more information, read our analysis of what the varying experience of different cities tells us about the trajectory of the pandemic, and our explainer on how to interpret these charts. We have also addressed concerns that have been raised about using case data to make geographic comparisons.

City Observatory presents here its estimates of the prevalence and recent growth of reported Covid-19 cases in large US metropolitan areas.  We update this page regularly with the most recent available data.  The data on this page was last updated with data on counts of cases through April 28, 2020.  Caution should be used in interpreting these figures.  Case data can vary from the actual incidence of Corona virus infections due to differences in testing regimes and availability across jurisdictions, as well as other factors.  We believe that metro area levels and trends may be a useful geography for understanding the spread and intensity of the pandemic:  most published data are available at only the state or county level.  States are too large to accurately capture the the incidence of the pandemic; and counties are often too variable and too small.  Metro areas capture labor markets and commuting sheds, and are defined consistently, making them more appropriate geographic units for judging the spread of the virus.  As is our common practice at City Observatory, our focus is on metro areas with populations of 1 million or more.

Metro areas ranked by reported Covid-19 cases per 100,000 population

The following chart shows the number of reported cases of Covid-19 cases per 100,000 population is US metropolitan areas with a population of 1 million or more as of April 28, 2020.  Metropolitan data are computed by aggregating county level data available from The New York Times.  Metropolitan areas are ranked highest to lowest according to the number of reported cases per capita.

New York, New Orleans Detroit and Boston have the highest number of cases per capita of US metro areas.  New York has the highest rate of cases per 100,000 population (1,921). New Orleans’s rate is currently 1,251 cases per 100,000. Boston (916) and Detroit (676) rank third and fourth in cases per capita.  The median large metropolitan area has about 164 cases per 100,000 population.

Map of metro areas, reported Covid-19 cases per 100,000 population

The following map illustrates the relative number of reported Covid-19 cases per capita among large US metropolitan areas.  Darker red colors indicate metro areas with the highest reported incidence of cases.  Numbers on each metro area represent cases per 100,000 on April 28.

Our regional analysis shows that the Northeast Corridor has emerged as a significant hotspot for the pandemic, with reported cases per capita and recent growth in the number of reported cases both exceeding the average for all metro areas.

How many new cases?

As our efforts to limit the spread of the pandemic proceed, a key variable is how many new cases are reported each day. This is a somewhat noisy data series because of variability and lags in reporting processes in different places, so these daily number should be interpreted with caution.  This analysis counts the number of new cases reported in the last day per 100,000 population.

As before, we’ve ranked metropolitan areas bases on cases (here new cases) per 100,000 population.  These data are for new cases reported on April 28. The median large metropolitan are reported about 4.8 new cases per 100,000 population, with half of metro areas reporting between 2.8 and 7.1 new cases per 100,000.  The highest rate per 100,000 population of newly reported cases were in Providence (33) Boston (27), Grand Rapids (26) and Philadelphia (25).  Four of the five highest rates of newly reported cases were metro areas in the Northeast corridor.

Growth Rates

A less noisy but somewhat more lagging indicator is looking at the average daily percentage increase in the number of cases over the past week.  We track this indicator over time to see which cities have made progress in reducing the growth rate of the number of reported cases.  This chart shows growth rates for the metro areas with the greatest prevalence of reported Covid-19 cases.

Rates are trending down for nearly all cities, but still must continue to fall further to blunt the pandemic.

Prevalence versus Growth

The severity of the pandemic in any location can be summarized by looking at two factors:  the overall cumulative number of cases per capita and the current rate of growth in the number of reported cases. Here we’ve plotted the current prevalence of reported cases in each metropolitan area (shown on the horizontal axis) against the growth rate of reported cases in the past week in that metropolitan area (on the vertical axis).  The number of cases in each metropolitan area is proportional to the size of the circle representing each metro area.  You can mouse-over individual circles on the chart to fully identify each metro area, and see the underlying data for numbers of cases, cases per 100,000 and the growth rate in cases over the last week.

We’ve used the means of the two variables (growth rate (3.5 percent daily) and number of reported cases per 100,000 (269), to divide the chart into four quadrants. These quadrants help sort out which metro areas are experiencing the crisis to a greater or lesser degree.  Metro areas in the upper right hand quadrant are clearly most afflicted:  they have both higher than average rates of cases per capita and are growing faster than the average metro area (in the past week).  The lower right hand quadrant identifies metro areas with relatively higher rates of reported cases per capita, but slower rates of increase.  Ideally, one wants to be in the lower left hand quadrant (low number of cases per capita, low growth rate).  The upper left hand quadrant is uncertain, but with cause for concern:  these cities (so far) have lower rates of cases per capita, but are seeing the virus spread faster than in the average metro area.  Over time, the strategy of flattening the curve should lead individual metropolitan areas to progress from the upper left hand quadrant (low rates and fast growth) to the lower right hand quadrant (higher than average rates but a slower rate of growth).

To make this picture a bit clearer, we’ve shortened the horizontal scale to exclude cities with the highest numbers of cases per capita.  This chart makes it clearer which cities are in which quadrants.

Notes and revisions

This post updates and supersedes our earlier posts with data through April 28. Data for our analysis comes from The New York Times database of county level reported Covid-19 cases.

The charts and information presented here on published data from state health departments, aggregated by The New York Times. Please use caution in interpreting these data. It is likely that in some areas, the number of cases is under-reported due to the lack of available testing capacity, or pressing medical conditions.  There are widespread differences in the number of tests administered relative to the size of the population in each state, and tests are not given randomly, and may be restricted solely to persons with symptoms, likely exposure or high risk in some states.  As a result, the ratio of reported to unreported, undiagnosed cases may vary across geography.  Moreover, changes in reported numbers of cases from day to day or week to week may reflect changes in the availability or application of testing over time, rather than the true rate of growth in the number of persons affected.