North Dakota's population registered a 3.1 percent uptick between July 2012 and July 2013, the largest increase of any state. The state was followed by the District of Columbia (+2.1 percent), Utah (+1.6 percent) and Colorado (+1.5 percent) as the top population gainers.
The Census Bureau computes state population estimates using multiple data sets. Population estimates by state, current as of July of each year, include birth rates, death rates and estimates of residents migrating from one state to another. (For a more detailed explanation, refer to the Census Bureau's methodology here)