Kevin,
OK -- I've done a bit of reading up on appropriate screen type of trees. Unfortunately, I couldn't find anything on Ameri-Willow. This may be a more generic name for a traditional species whose name is harder to pronounce. Marketers do this at times for selling purposes which today's consumer can better relate to.
The following are other possibilities for very fast growing trees...in no particular preferred order. Bat Willow (Salix caerulea), Black cottonwood (Populus trichocarpa), Crack Willow (Salix fragilis), Lombardy Poplar (Populas nigra), and 'Robusta' poplar (Populus 'Robusta'). I've only given you ones here that I think would adapt well to Michigan's soil and climate. Only drawback to all of these are they are angiosperm varieties, in other words trees that shed their leaves in the fall and winter months. This being the case, I think you would want to go with gymnosperm varieties...or needled trees that maintain foliage all thoughout the year.
This being the case... I still recommend the White Pine (Pinus Strobus). These will grow 1'-2' per year when young. Despite it's cabbage tree tendencies, if planted close together these trees will grow close together from tree base to upper canopy and give you a nice tree screen. Another gymnosperm variety you may want to consider is Austrian Pine (Pinus nigra). These are a fast growing European import (again 1'-2' growth per year) which have adapted well to American climate and soil conditions. Many of the conifers you see planted alongside state highways after road reconstruction are Austrian Pines. They are not susceptible to White Pine Blister Rust, very tolerant of poor air quality or air pollution, very adaptable to most soil and moisture conditions. They are beautiful landscape or speciman trees but will also do well as a screen if planted in a staggered format...maybe spaced out a bit more than the White Pine...that is 8-10' vis-a-vis 6' for White Pine. The only drawback to these are those white tailed critters love to munch on the tops and branches. If you go with these, you'll have to fence these in when young, especially if you have a deer problem.
I've ordered many trees from Musser Forests. See link below. Order their free catalog, but also browse the website...it's highly educational and will give you pretty much all the information I think you're looking for on trees which are very fast growing. The trees can be ordered in lots of 10, 50, 100, or 500 I think. The more you order per lot, the less expensive they will be per tree. Also, order them if you can as transplants, not seedlings. Transplants are a bit more expensive but they are bigger in size when you receive them and they are more durable than the seedlings...that is they have a greater chance of surviving the first year.
<A target="_blank" HREF=http://www.musserforests.com>http://www.musserforests.com</A>
Hope all this helps. Wow, this brings back good memories from my forestry school days at Utah State Univ. Wish I was working in the field...but back in the 70s the jobs just were not there. Let me know if you need further advice. I'll try to help any way I can.
Bob