Washington-Scoot over, Nevada! Arizona has ended your 19-year reign as the fastest-growing state. We were the rightful champion last year, too, only we didn't get credit until today, when the Census Bureau released updated figures. Arizona had a population growth rate of 3.6 percent in 2006, census estimates show. It added 213,311 people, including about 32,000 immigrants and 130,000 people moving from other states. That brings the population to more than 6.1 million and makes Arizona the 16th largest state. The nation's biggest population loser: Hurricane Katrina-ravaged Louisiana. "We're proud to be Number 1," said Jeanine L'Ecuyer, a spokeswoman for Gov. Janet Napolitano. But adequate roads, housing, schools and water are part of managing the growth, she said. The South was the biggest regional gainer, picking up about 500,000 people. The West added 53,000 people from other parts of the United States. The Northeast lost 375,000, and the Midwest lost 184,000.