Complex sentence: It has been rated as the wealthiest city in the United States by CNN Money, and the United States Census Bureau declared Plano the wealthiest city of 2008 by comparing the median household income for all U.S. cities whose populations were greater than 250,000.
Split into simpler sentences: It has been rated as the wealthiest city in the United States by CNN Money. The United States Census Bureau declared Plano the wealthiest city of 2008 by comparing the median household income for all U.S. cities whose populations were greater than 250,000.