The current U.S. federal minimum wage is $7.25 per hour for covered, nonexempt employees. The rate was set by the Fair Minimum Wage Act of 2007 and reached $7.25 on July 24, 2009; Congress has not raised the federal rate since.
The federal minimum is a nationwide floor under the Fair Labor Standards Act, or FLSA. States and cities may require higher wages, and workers generally receive the highest applicable federal, state, or local rate. Employers covered by the FLSA must follow the federal rule even where local law provides additional protections.
The federal rate is not identical to every wage rule. Tipped employees may be paid a lower direct cash wage if specified conditions are met, including proper tip-credit treatment, while some occupations and workers have exemptions. Overtime rules also generally require time-and-a-half after 40 hours in a workweek for covered nonexempt employees.
The $15.00 figure is a proposed or local rate in some contexts, not the current federal standard. The old federal rate of $5.15 was superseded in 2007.