Table 1. Population Access to Proton Beam Therapy Facilities by Driving Time Categories in the United States.

Driving time to proton beam therapy facility, h	Population, millions, No. (%)
0 to <1	119.8 (36.6)
1 to <2	67.7 (20.7)
2 to <3	45.3 (13.8)
3 to <4	41.1 (12.6)
≥4	53.6 (16.4)