Digital BW, The Print

You will note that the TSA document refers only to how many bags you 
can check THRU SECURITY. It has no bearing on what the individual 
airline will allow onboard as far as number of carry-on bags is 
concerned. The TSA document says something to the effect that you 
should check with the individual airline about their restrictions; 
that is, how many bags you can carry on and how big they can be.