Western Australia (Australia) is 551 times larger than Harris County, Texas.
Western Australia is a state occupying the entire western third of Australia. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Southern Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east. Wikipedia
Area: 4,589 km2 calculated
Harris County is a county in the U.S. state of Texas. As of the 2010 census, the population was 4,092,459, making it the most populous county in Texas and the third-most populous in the United States. Wikipedia