As part of my construction of a population projection for North Dakota my reading and data analysis focused significantly on demographic data and trends in North Dakota. One of my concerns with trends in North Dakota is that with a low population base even moderate flows will lead to rate changes and possible adjustments in trends. The other issue for North Dakota is that the proximity to a larger neighbor in Minnesota can somewhat complicate the analysis. For example, this graph.
This graph displays migration into North Dakota from other states, or at least it is supposed to. The share of total in-migration to North Dakota accounted for by Minnesota compresses the scale somewhat and it is difficult to make out the contributions of any other state. The problem for projecting will be a topic for later. For now, I remove Minnesota from the set of states and adjust the total inflow for the state’s absence.
So there are now four or five states in play, obviously excluding Minnesota. South Dakota and Montana are not too surprising. California and Texas might be a surprise to some though being the largest two states it would seem likely that they would be large for almost any state. Nebraska was a bit of a surprise though. There is an influx from many other places too, but not at the scale of these others.
The same type of situation exists for migration out of North Dakota. The inclusion of Minnesota ends up compressing the scale on the map so much there is not much interpretation possible.
I take the same step this time and we get a similar, better map.
The outflows are some of the very same states from which we saw significant inflows earlier. Newly important states include Colorado, Washington, and even Florida. Not so much of a surprise given the warm weather retirement plans of many that spend a career here. This does create a question about the overall flow, that is both in and out.
Rather than concern myself with net flow at this point I decided to look at the overall size of the flow, inflow added to outflow, as a share of the total flow. Once again, the proximity to Minnesota creates a problem.
While clearly a few states like California are important, Minnesota dominates all with around 33% of the total inflow and outflow into and out of North Dakota.
California and South Dakota look to be very important once we exclude Minnesota. Texas, Montana, and Washington come in as a second tier of states with large flows with North Dakota. What is most remarkable is that the entire eastern United States seems to be in a very low transition state between them and North Dakota. That is really surprising.
Consequences for Projection
So what has me really concerned is the enormous flows between Minnesota and North Dakota. I suspect these flows are likely to create problems for my projection of the North Dakota population. The permanency of the migration, both in and out, is questionable and would present significant potential to influence demographic rates.