In a country the size of the USA, 300 miles probably doesn't seem a great distance, especially if you can travel 300 miles and still be in the same state.
If you are on Interstate 10 in Texas, you will travel nearly three times that...and the entire part of that is in Texas! It is ~650 miles to El Paso from where I am, and I would be in Texas the entire time.
I-20 is at Exit 178 on I-10, and I-30 is Exit 421 on I-20. Whether you go from El Paso to Texarkana/Waskom/Beaumont, the distances are all over 800.
El Paso to Texarkana: 822 miles
El Paso to Waskom: 814 miles
El Paso to Beaumont: 880 miles (all I-10)
I drive 23 miles to work each day one way. There are only 3 states that I know of that has any mile markers on interstates over 500: California (I-5), Montana (I-90), and Texas (I-10, I-20, and I-35).