I'm in Canada, but I googled 3Telsa MRI machine and found the hospitals that had the machines here. Hope that helps.
I downloaded the list of approved radiology centers in my insurance plan and area. I eliminated all those that had "open" in the name because they're the weakest. Then I started trying to look all of them up on the web--if they said what their machine was, I could look up the model on the mfr's web site, if they didn't outright say its strength.
A member here suggested I contact the manufacturer (like Siemens or GE) and ask about where they have installed 3T units. However, I lucked out by calling one of the survivors from my list--the tech told me theirs was a 1.5 T, but he also told me where a local 3T was. So by the process of elimination, I got it down to one call! Granted, luck was involved.
Have you looked into any Universities near you? I know UCLA has very good MRI imaging.
I found one in a hospital in Aventura, Florida. It is by Elite Imaging. You can call them about the exact location at (305) 692-2222 or on the internet at www.eliteimaging.net. One is in Aventura Florida in the Mt. Sinai medical arts plaza on aventura blvd.