H.R.6666 – Covid-19 Testing, Reaching, and Contacting Everyone (Trace) Act

Since this is a legal question, I did a search of the US Code and found a clue at https://www.law.cornell.edu/cfr/text/42/493.35 :

> "Laboratories that are not at a fixed location, that is, laboratories that move from testing site to testing site, such as mobile units providing laboratory testing"

So in this case, it might be a temporary facility, perhaps in a trailer at a local parking lot, used to monitor cases.