Houston is the largest city in Texas, the fourth largest city in the United States, and the largest economic center on the Gulf Coast. It has an area of 1,440  square kilometers and a population of about 2.2 million. The city is named after Sam Houston, the president of the Republic of Texas that year. Houston’s official nickname is “Space City” because it’s home to the Johnson Aviation Center, which is also home to Mission Monitoring. Therefore, “Houston” is the first word spoken on the moon.