That's earning federal minimum wage. 29 States, including many of the most populous states, have higher minimum wages.
> The CPS does not determine whether workers are covered by the minimum wage provisions of the federal Fair Labor Standards Act (FLSA) or by individual state or local minimum wage laws. The estimates of workers paid at or below the federal minimum wage are based solely on the hourly wage that respondents report (which does not include overtime pay, tips, or commissions). It should be noted that some respondents might round their hourly earnings when answering survey questions. As a result, some workers might be reported as having hourly earnings above or below the federal minimum wage when, in fact, they earn the minimum wage.
> Some workers reported as earning at or below the prevailing federal minimum wage may not in fact be covered by federal or state minimum wage laws because of exclusions and exemptions in the statutes. Thus, the presence of workers with hourly earnings below the federal minimum wage does not necessarily indicate violations of the FLSA or state statutes in cases where such standards apply.
> Estimates of the number of minimum wage workers in this report pertain only to workers who are paid hourly rates. Salaried workers and other workers who are not paid by the hour are excluded, even though some have earnings that, if converted to hourly rates, would be at or below the federal minimum wage. Consequently, the estimates presented in this report likely underestimate the actual number of workers with hourly earnings at or below the minimum wage. BLS does not routinely estimate the hourly earnings of workers not paid by the hour because of data quality concerns associated with constructing such an estimate.
> Several states have established minimum wage rates that exceed the federal level. (Information on state minimum wage laws is available at https://www.dol.gov/agencies/whd/minimum-wage/state.) Users should be cautious about comparing state estimates with CPS estimates in this report because of differing statutory minimum wages. It also should be noted that the CPS sample is based on residence; workers report their earnings on their job, which may not be located in the same state in which they live. In addition, the degree of sampling error may be quite large for some state estimates.
I’m sure a sizable portion of them are students.