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Projecting Marin County population out to 2300

I recently published an article at Medium Will China Survive till the Year 2300? Possibly not! I figured I would leverage some of the methodologies I used within this article to project the population of Marin until the year 2300.

Within earlier articles in the Marin Post, I observed that Marin's population growth since 2000 had nothing in common with California and the US (see left-hand graph below). Marin's population has grown far slower. Instead, Marin's population growth is far closer aligned with Italy (right-hand graph below), a country with aging demographics similar to Marin County.


Using one of the methods displayed within my Medium article, I calculated the 25-year population % change for both Italy and Marin.


Focusing on the graph above, for Italy I used the UN Population Division Medium and Low fertility scenarios; that go out to 2100. For Marin, I used the natural growth rates forecasted by the California Department of Finance (DoF); and I used a neutral migration rate (0%). For more detail on this forecast, please refer to my earlier article at the Marin Post Sacramento projections for the Bay Area are still much too high. This forecast goes out to 2060. Next, I extended this forecast to 2100, so the 25-year change in Marin population falls pretty much in between Italy's Medium and Low scenarios.

Next, I did exactly what I had done in the Medium article, and that is to assume that the 25-year population growth rates reverted to 0% by 2300. By itself, that is a rather heroic assumption that assumes that both Italy and Marin would eventually be able to reverse their respective rapid population decline associated with aging demographics, including low fertility, and little assistance from migration. Using the resulting 25-year population growth rates, one can readily construct the resulting population level for any year from 2101 up to 2300.

Now, it is time to review the output from this simple forecasting model. By design, Marin's drop in population falls somewhat in between the two scenarios for Italy.


The tables below capture the same data shown within the graph.

Table-Y.pngAs shown above, just like Italy, Marin's population would experience a drastic decline till 2300 ( - 78% for Marin, and between - 63% and - 86% for Italy depending on the scenario).

Both Marin and Italy would experience about 2/3ds of their respective population decline by 2100. And, they would experience over 90% of their respective decline by 2200.

Extending the forecast for an additional century (from 2200 to 2300) did not turn out to be punishing. This is because the negative population growth rates become progressively closer to 0%. Thus, the respective populations do not contract that much more between 2200 and 2300.

One can wonder how Marin could avoid this continuing drop in population.


Marin County, demographics, Italy, population decline