There is a positive relationship between discrepancy and growth rates, but it is not as strong as one might have guessed. Because migration is notoriously hard to accurately project, one would assume that states with large net migrations from other states would also be more difficult to accurately project. This suggests that high net domestic migration causes difficulties for projection, but their nature is not simple. But in their midst are Alaska, Hawaii and the Dakotas. The simple correlation coefficient between discrepancy and domestic net migration is .232, which is not significant.
International migration is among the more difficult variables to project.
Several of the most under-projected states have reasonably large net migration rates, including California, Washington, D.C., New York, New Jersey, Florida, Rhode Island and Connecticut. It appears that the Census Bureau's projections are like most other projections in under-projecting observations with the largest inflows. The simple correlation between international net migration and discrepancy is plus .523. This is the strongest of the direct correlation with discrepancy. Thus, at least one hypothesis holds water.