Here's a guest article from buckshot.jones' excellent Detroit Journal.

Here's the process of prairiefying a city:

1. A city is built on the river, allowing for trade and commerce and irrigation of farms.
2. The city prospers and more people move in, the city expands. Farms on the edge of town are converted to housing, forest further on the edge are cleared for farms.
3. Over a few generations this process repeats.
4. A lightening bolt of innovation strikes the heart of several men at about the same time (Henry Ford, The Dodge and Fisher clans, Henry Leland, Billy Durant and the crowd from Flint, et al), and all hell breaks loose, suddenly the timber town on the River is an industrial gold mine.
5. An insane number of people flow in from all parts of the world. Black and white folks roll in from the south. All the farms are snatched up and houses, mills, factories and shops are planted in the field.
6. Everyone wants to drive and the emotional tie of the car to an entire nation is so intense the money whooshing through the city is almost palatable. The wealth is spread around and the workers decide to spread out, move out to the “country”. They have the means to do it, these middle class kings.
7. Then one day the money flow slowed down. Innovation and competition meant fewer jobs. Factories began to close. New factories followed the workers out to the “country”.
8. Too many people left behind lacked the money and prospects to maintain their homes and in the Michigan climate a home requires money to keep it standing.
9. Slowly at first, then faster as time passed, neighborhoods were simply deserted.
10. As folks moved out, businesses and churches and such that needed them soon closed their doors. With no buyers for their stores, they stood abandoned.
11. One by one these homes, factories and stores fall victim to the elements and arson. In time entire blocks are cleared. Native grasses and trees take root.

A city is built on the river, allowing for trade and commerce and irrigation of farms.....