Here is a link to one of the more recent shrimp threads.
If you go down to about the 8th post, there is a link to an even more comprehensive shrimp thread.Shrimp Thread - Pond Boss
There are several species of freshwater shrimp in the U.S. I believe there are some suppliers that carry the species more adapted to cooler, northern waters. I think people have reproducing populations as far north as Nebraska, and perhaps some members north of that? (I believe Long Island and southern Nebraska have roughly the same "average" annual temperature. Further, I believe Nebraska is more likely to have bitter cold snaps, but I could easily be wrong on that!)
If you enter the function for "Advanced Forum Search", you can put shrimp in the box for Keyword Search Terms, and then select the dot for Search Title Only. That should get you about 3 pages of "shrimp threads" to read, if no one replies with a very specific answer for you. It might also be helpful to read up on the type of pond habitat that was present for the people that created thriving shrimp populations.
Good luck on getting grass shrimp stocked into your pond. It should make your fish very happy!