I found this to be interesting. I-95 in SC has its 100 mile marker over water. However I find more interesting the fact that I-95 100 miles to the south also is over water.
Any other freeways that have this.
(https://live.staticflickr.com/65535/50951745657_a772ab733f_k.jpg)
Not sure about mile marker 100, but I'm pretty confident I-90 near Seattle has a mile marker or two over the water.
In Indiana,
I-64 comes closest. MM 0 is over the Wabash River and MM 99.9 is over the Blue River.
If you're willing to count drainage ditches as bodies of water, I-65 is over the Ohio River at MM 0 and a drainage ditch at 100.2
I don't think Michigan has anything as none of the borders on the south and west are over a body of water. The west side of course has Lake Michigan but there isn't any Interstate running over that.
D'oh. Misread the post before replying. Apologies. 😬
This one is not exactly 100, but pretty close: I-71 crosses the Ohio River at mile 0 and the Scioto River at mile 106. But, I-71 uses I-70's mile markers and exit numbers at where it crosses the Scioto, and I-70 is at mile 100 at that point.