Most people in the United States earn income through being paid per hour of labor, as well as through being paid a yearly salary for meeting certain objectives. Both options are common forms of compensation for employees in various industries. However, the most prevalent form of income for hourly workers is typically through hourly wages.
If you are looking for the most common way across all workers, it would generally be being paid per hour of labor for many jobs, especially in entry-level and service positions.