This is quite true about a map of the distribution of the cases will, over time, mirror a heat map of the population density.

I was not very clear about the point that I was trying to convey and I apologize for that.

I was attempting to make the point that the evolution of the map, with the daily updates, lends credence to the idea that a single infected person could be the source of the cases in multiple scattered areas and across several state lines.

I have followed this map and the updates since it was first added to the Reuters site. As expected, the first cases appeared very isolated and confined to the immediate area around King County, WA involving, I think, the care worker at the nursing home.

As the map evolved, other hot spots appeared.

In the last 4 or 5 days it has really begun to fill out to the point where the east coast has many contiguous counties with cases, the west coast also has filled out and the mid-continent likewise.

It was possible, if one followed the progression to see counties report cases that connected larger outbreaks with each other as the smaller cities between suddenly had something to report.

Today was a great example of that. This morning there were cases in western New Mexico in one county. This afternoon, we can suddenly see I-40 highlighted east-west and I-25 highlighted south-north into Colorado.

I realize that testing in every state is ramping up now so it is likely that none of those counties had any cases to report previously because they had run no tests and now they all received test results at the same time.

The interesting thing, having driven many of these highways myself over the years and some of them recently is that te spacing of the cases (new counties reporting) matches the approximate distance one would drive before needing a break for food, a restroom, or just a chance to stretch one's legs. When a connection appears between two larger cities in a way that fills in a case for each potential pit stop then it might be plausible that one traveler is responsible for that connection.

For example: Covid Mary starts in Dallas - destination Omaha. It's about a 10 hour drive most of which can be made on I-35. They may need a stretch just before or just after they roll into Oklahoma. Then the stops are Oklahoma City area; Wichita, Kansas; Emporia, Kansas; Topeka, Kansas; Omaha, Nebraska.

At each stop Mary gets gas, goes inside the store for a restroom break, goes in for a greasy taco or burger. Each time she goes in she grabs a door handle, a pump handle, a cooler handle, etc that has had hundreds of hands on it since the last cleaning and will have hundreds more until the next one. She isn't feeling particularly sick, yet anyway, but she has been coughing a bit into her hands as she drives.

Some random person who was unlucky enough to stop after she stopped at the various businesses grabs these handles or items that she has touched and then becomes a spreader. For them, the clock has just started before they get sick or before someone they contact gets sick. In a matter of days, some of these people grabbed the viral load from Mary's handle and carried it around to their families. Eventually one or more of them became sick enough to seek help.

When test results are posted, they highlight this travel path.

All the spread could've been mitigated if materials known to have anti-viral or anti-bacterial qualities had been used in the design and construction of the facilities visited by Covid Mary.

It was just a thought.

EDIT: The main idea was that Covid Mary took a trip between two larger cities. The journey involved multiple stops. In each town where she stopped someone became a carrier. That carrier spread to others in the small towns of the area. Once tests were available it was possible to see the route Mary - a single ill traveler on a long day's journey, traversed between where she was and where she wanted to be. Since the time of infection was similar for all of them they all appeared on the map at the same time. You know, this sounds dumb and I'm tired now. Thanks for reading if you made it this far.