No valves exist between the anterior vena cava and the heart, and the heartbeat tends to cause movement within this blood vessel. Another vessel, the posterior vena cava, carries blood from the lower half of the body to the heart.
The 2016 Hereford, Texas, population is 15,021. There are 2,447 people per square mile (population density).
The bulk of the city is in Dallas County, of which it is the county seat; however, sections of the city are located in Collin, Denton, Kaufman, and Rockwall counties. According to the 2010 United States Census, the city had a population of 1,197,816.