A stirring but controversial period of American history ended, semiofficially, on this date in 1893. That’s when University of Wisconsin historian Frederick Jackson Turner delivered a landmark academic paper in Chicago. Based on 1890 Census data, Turner declared that the closing of the American frontier ended the formative national experience. Turner said that migration from the East, the building of railroads and hundreds of new towns had combined to forge a single transcontinental nation. Even 123 years on, the West remains a magnet for population migration. Between 2000 and 2010, Nevada was the fastest growing state at 35 percent. Other states that grew more than 20 percent were Utah, Texas, Idaho, and Arizona. Profile America is in its 20th year as a public service of the U.S. Census Bureau.