It is 600.08 miles accordiing to MapQuest.
It is 644.35 miles via Fort Worth, Wichita Falls and Amarillo according to MapQuest.
600 miles taking this route:Follow U.S. 287 SOUTH from Amarillo to I-45 SOUTH to CORSICANA in Ennis, which is about 35 miles south of Dallas.Take I-45 SOUTH to Houston.
Amarillo is a city in Texas.
60.3 miles
334 miles
490 miles
The great circle distance from Amarillo to Honolulu is about 3500 miles.
375 miles.
It is 705 miles.
725 miles
Knowing exactly where in Texas would help a lot. Texas is an extremely large state, and there's going to be a substantial difference between Houston and Amarillo.
It is 650 miles according to Google Maps.