The census of that year clearly indicated that the population of the Northern, free states was fast exceeding the rate of growth in the Southern slave states. This could have been predicted a decade earlier, but the tide of immigration had greatly increased, bringing many new persons to the cities of the North. Boston, Baltimore, Philadelphia, and Newport had all grown, but the big winner was clearly New York City. Not only was it already the most populous place in the nation, but it bid fair to outdistance all its rivals, to become the metropolis of the country.

The census of 1850 also indicated the strength of New York State as a whole. The Empire State—the term had already appeared—increased from a population of 2.4 million in 1840 to 3.1 million in 1850. Such growth had never before been seen. Other Northern states showed similar patterns of growth. Pennsylvania, for example, increased from 1.7 million persons in 1840 to 2.3 million in 1850. In terms of free population, but also of total population, the Northern states were clearly winning the race against the Southern ones.