Personally, I know real well where the mosques in my area are. Where no muslims resided at all, until they bought the buildings (often churches) and made mosques out of them.
But thanks for posting the links, they are useful to some folks.
There are other ways to track these numbers as well. Consider exploring the website
RefugeeResettlementWatch to discover all the work visas and charities working to bring Muslims from across the globe into the United States. Each of these increasingly expanding immigrant communities establish 'off the radar' (so to speak) support systems which eventually demand/require the importation of extended family members (chain migration), religious service support, etc. And it all takes place, right under our noses.