The design bug bit me again in the shower yesterday, so I did some more preliminary design ideas for Michigan, and I'm at the point now where I might do a rough draw of the map up and start toying with the mathematical design of the map and expenses. I thought I had a rough map around here, but it seems to have completely disappeared, which means I am going to have to dig deeper into the paper piles, or completely redraw it...otherwise I would have attached a VERY rough draw to this post.
In any case, in the initial draw, Cities on the map will have coloured squares to denote what they can Produce. Their primary (normal) colour will be what they accept during delivery.
Goods Growth phase will be like Australian Railways, each player will draw a cube (a couple, a few) from the bag, and place 1 on any legal spot on the map, the legal spots being denoted by the production colour squares.
Before the Growth phase, but only in the late rounds (say, 7+, game being 10 rounds) there will be a check for Blight. An area becomes Blighted if it only has 1 (or 0) good(s) remaining. In that case, that remaining good is removed, and a neutral player stone is placed on top of the city. It no longer can produce goods, it can no longer accept goods, and any good that passes through it during delivery is worth 1 less income.
I am strongly considering unique New City tiles, otherwise, I will make the New City tiles only accept goods.
I anticipate that Blight will make the end game rather nasty indeed, as making income would suddenly become insanely difficult, particularly if paired with the accelerated expenses idea. I might just work with Blight alone before trying to add more expenses on top of it. My guess is that Blight will create tendencies for players to load up distant Cities with their production, hence trying to protect themselves for the late game. The southern portion of the board will thus, start out lucrative (more goods at the start of the game) but will likely die by the late game because the goods will be missing and it will become Blighted, and hence, very difficult to ship through at a profit.
If Blight ends up becoming too nasty, it could always be mildly toned down a bit...for instance, cities that are Blighted could still accept goods, and the -1 income hit could only be something that hits a cube once, when it is delivered to a Blighted city, rather than leeching income each time a good passes through.
As an addendum: Chicago and Green Bay will never be subject to Blight. Green Bay will be served only via a Ferry Line from Ludington. Chicago will have a ship line connected to it from the UP, but will also be reachable with track.