50 miles is a US government defined "commutable distance" (I was just talking about this at work with a human resources person, but unfortunately I can't recall what agency defined it as such).

Maybe OPM: (U.S. Office of Personnel Management)

https://www.opm.gov/policy-data-oversight/pay-leave/work-sch...

Official Duty Station

An agency may prescribe a mileage radius of not greater than 50 miles to determine whether an employee's travel is within or outside the limits of the employee's official duty station for determining entitlement to overtime pay for travel.