Amarillo, Texas is 4.1 times larger than Pomona, California.
Area: 257 km2 calculated
Amarillo is the fourteenth most populous city in the state of Texas, also the largest City in the Texas Panhandle, and the seat of Potter County. A portion of the city extends into Randall County. The population was 190,695 at the 2010 census. Wikipedia
Area: 63 km2 calculated
Pomona is the fifth largest city in Los Angeles County, California. Pomona is located in between the Inland Empire and the San Gabriel Valley. As of the 2010 United States Census, the city's population was 149,058. Wikipedia