Geography is destiny

Frequent commenter Michael commented that the supply chain is vulnerable to cities-as-choke-points.

While I am not going to dispute that point, I want to demonstrate that the funnel or choke-point effect is highly dependent on geography.

First, some maps

Columbus, Ohio is in the middle of Ohio and the topography is relatively flat. I-70 is a major artery for commerce and it runs pretty much through the center of Columbus from East-to-West.

Later build-out of the Interstate plan has a "ring" around Columbus with a minimum "radius" to downtown of five miles. Then, minor Interstates and state highways act as spokes radiating out from the downtown area.

From a logistical and supply-chain perspective, this looks pretty robust to me.

This is another map of Columbus and it shows the location of all of the Walmarts. Most of them are located close to an intersection of a "spoke" and the ring-Interstate. You can trash-talk Walmart all you want, but they are really sharp when it comes to logistics.

A map of Indianapolis, Indiana. It is not as busy as Columbus but it follows the same general plan. You might notice that the ring is lopsided. If civil disorder snips the ring at the closest point (five miles from downtown) then they would have to project their force almost four times farther to snip it at the northernmost stretch.

St Louis, Missouri is a little more complicated. The Mississippi and Missouri rivers come into play but there is still a generous ring around the core-city.

Even small cities with relatively little strategic importance like Lansing, Michigan have this "ring" structure. Traffic from Chicago-to-Canada bypasses Lansing by taking the west, then northern legs around the city.

One thing that all of these cities share is that they sit on relatively flat land.

Blue line approximates I-70. Green line approximates I-76. Plum-colored lines approximate other Interstates

That all falls apart when you get to hilly terrain. Pittsburgh was built in hilly terrain at a time when water transportation was strategically significant.

While the Pittsburgh area is laced with many roads, the wrinkles and folds of the landscape makes them a nightmare to bypass. That kind of landscape favors the resistance and potentially handicaps the wheels of commerce.

Topography of southern New England and eastern New York

Many of the "classic" cities in New England and New York are compressed in the east-west direction because they are shoe-horned into the Connecticut and Hudson river valleys due to water power and transportation. That makes the lazy-ring + bicycle spoke arrangement uneconomical.

Springfield, Massachusetts. Blue lines approximate interstates. 5-mile measurement bar added for scale.