LyrArc Article Gist
Metro Detroit has 90% of the 17,000 cases in Michigan as the pandemic reaches its peak there this week. 

The large Detroit airport renovated and enlarged is seen as a source of the coronavirus as Detroit is where all 3 auto U.S. auto companies are located. GM, and Ford have large manufacturing operations in China, and  Chrysler has plants in northern Italy, the locations where coronavirus has hit hard, and in the case of China where it originated. Health experts say the busy Detroit international airport connecting the Detroit hub to other auto hubs in northern Italy and China- both virus hotspots- may have contributed to the virus hitting Detroit early.

This country to country transmission along some route is how the virus has traveled to over 150 countries. For instance German reports show Bavaria as the source of the early cases in Italy's Lombardy region. It could be that German auto companies located in Bavaria with large operations in China resulted in inadvertent transmission of the virus from China through airport in Munich from flights between Germany and China. A Shenyang municipal bureau report provides information on German  investment in Shenyang, Liaoning province. Munich based BMW makes 1.3 million cars here. There is also the newly built Chinese German Tiexi industrial park in Shenyang with 50 German companies BASF, Siemens, located there. 

Once the virus arrives in one location its spread depends on the environment with densely packed areas and the health conditions prevailing in a particular area playing their part. Both in New York and Detroit metro area this helped its faster spread in lower income densely packed areas.