From what I see, this is based on median income for those working. And not taking into account employment rate, for example. Or cost of living. Which the article does list for each state discussed.
Richest
1.Maryland 72,483
http://money.msn.com/investing/americas-richest-and-poorest-states-1The wealthiest state in the U.S. last year boasted a median income of $72,483, compared to a median income of just $37,963 in America's poorest state.
Much of that comes from the fact that Maryland is right next to Washington DC, and where most of the companies that do government contracting reside. Potomac and Bethesda are the wealthiest areas of Maryland, bordering the DC beltway. So you can look at Maryland being #1 as being analogous to Maryland being most supported by US tax dollars.