Dallas, Texas is 430 feet above sea level
the height of land above or below the level of the ocean or sea level
Dry land is usually above sea level.
The sea is at a particular level compared to land. Most land is above sea level (or it would be under the sea or very far inland). If you are a mile above sea level, then you are a mile above where the sea would be if there was no land there.
Bastrop, Texas is 367 feet (112 meters) above sea level
if the land surrounding the sea is below sea level
Texas borders the Gulf of Mexico and therefore has a lot of land closer to sea level. The lowest point in Colorado is 3,317 feet above sea level. Texas has an average elevatiion of 1,700 feet above sea level compared to Colorado's 6,800 feet average elevation.
We call this "elevation".
Marfa, Texas is 4,685 feet (1,428 meters) above sea level
Dallas, Texas is 430 feet above sea level
Sea Level is at 0.00 feet as measured on the Gulf Coast.
Sea level.