Migration from liberal bastions in the Northeast and Midwest to the Sun Belt states will boost Republican electoral strength in the coming decade, making it tougher than ever for Democrats to win the presidency without carrying states in the South or Southwest. The Census Bureau's latest projection of population shifts, the first in eight years, shows a dramatic movement from the North to Southern and Western states over the next 30 years. The study points to a political movement as well. Heavily Democratic states such as New York, New Jersey, Illinois and Michigan will go on losing congressional seats and...