Perfect!
The process ended in an error so I lowered the number of simulations to 50
and it worked fine. I'll slowly bump up the number of realizations to
figure out what my clunky, old work computer can handle. I think it's my
computer, not the number of points I have (I only have 160 sites across the
contiguous U.S.).
Thanks again for you help. I could not have done this without your
thoughtful and detailed responses!