Being as objective as possible and having worked for Experian, I will say yes.

Americans, in aggregate, are one of the most monitored populations in the world^1. Financial institutions are painfully aware of the spending habits of Americans. I believe credit agency data, which is paired with monitoring bank accounts via social security tie-ins (that already exist), over census data. Integrate credit companies with social programs (like food cards) and you'll have a complete picture of the lowest brackets.

^1 China does better for specific demographics, but the rural populations are not tracked very well. I could also stand to be corrected for conditions in some very small countries.