Centerville, tx is roughly the half way point.
The halfway point between Dallas, Texas and Warren, Ohio is in Centerville, Tennessee.
A rough estimate would be Amarillo, Texas.
TENNESEE
denver Colorado
Panama city,fl
Four Corners, USA
The halfway point between Phoenix, Arizona and Dallas, Texas is Eagle Flat, Texas.
The town between Longview and Dallas on I-20 is Canton. It's in Texas.
hwy 71 and I10 west is a good halfway point, if you are traveling I10. Going 290, it would be where the Interstate makes a 90 degree turn (Im not sure of the town).
Hewitt, Texas
Waco is located in central Texas about halfway between Dallas and Austin.
There is approximately 738 miles between Austin, Texas and Destin, Florida. The city that halfway between these two cities is Lafayette, Louisiana.