Honestly, not that many! Maine’s population today is around 1.3 million people. But this graph obscures a lot of variation. So let’s look at just annual population growth rates.

Growth rates were very high in the late 1600s, then declined into the early 1700s. But then after British victory in the French and Indian War, growth picked up abruptly, remaining high through the American Revolution, when it began a precipitous fall. While the British had regulated settlement beyond the Appalachians, Maine had benefited from having a comparatively large amount of settleable land for the burgeoning Yankee population. But once new lands out west opened up, it lost its appeal, and growth plummeted. The decade of the 1860s actually saw Maine lose population. Unlike many states, Maine did not conduct a state Census in 1865–1867, so I can’t say how much of this decline was related to wartime losses and dislocations. However, it seems likely to have been substantial: approximately 1.5% of Maine’s 1860 population died as a result of the Civil War, and 11.2% were mobilized. That death rate is slightly higher than average for Union states. It is substantially higher than that experienced in Massachusetts, Connecticut, or Rhode Island, though about the same or a bit lower than the death rate seen in Vermont and New Hampshire. All of these states had similar rates of mobilization, but MA, CT, and RI disproportionately mobilized into the navy, where casualty rates were much lower.

It may surprise some readers to hear that the Union state with the highest Union-specific death rate, so exclusive of Confederate dead, was Kansas, at nearly 2.5% of its population having enrolled in the Union military and subsequently died as a result of the civil war. Illinois is next at 2%, with Indiana, Iowa, and Michigan just a hair behind. From there death rates drop sharply to around 1.5% for Minnesota, Ohio, Wisconsin, Vermont, and New Hampshire. The lowest Union death rates among Union states are observed for many of the western states like Colorado, Nevada, and California, as well as border states like Kentucky, Delaware, and Maryland, or maritime-heavy states like Rhode Island.

So the civil war probably accounts for a large share of Maine’s population decline. The ~10,000 war deaths alone probably account for more than 100% of the approximately 1,500 person decline in Maine’s population from 1860 to 1870.

Maine’s growth rates never make a historically game-changing rebound from the civil war. Modern population growth rates set in by the 1870s. So let’s zoom in on the post-1870 period.

From 1870 to WWI, Maine manages to have pretty steady population growth. Data quality improves in 1900, hence the spikier line. After WWI, Maine’s population returns to that trend growth rate, until WWII, when there’s a sharp fall. But then there’s a recovery post-war. Growth oscillates a fair amount in the 1950s and 1960s, but averages a little under 1%, similar to the previous periods. Finally, around 1970, Maine gets a fairly sustained growth period. There are boom-bust cycles, but from 1970 to the Great Recession, Maine manages to exploit its position as a low-regulation, low-tax, warm-climate Sunbelt state with big military-industrial investments during the Cold War to capture suburban expansion.

Hahahaha not. Actually they had basically none of those things. But they still managed to experience population growth until the Great Recession. They muddled through that period, but have recently returned to strong growth.

So what drives these trends?

Well, using a variety of data sources, we can try and tease out the components of population change. Here are my best estimates, going back as far as I can take them:

As you can see, Maine benefited from a substantial amount of international immigration, and lost domestic migrants pretty reliably, from 1850 through WWII. I should note that I think my 1924–1937 international migration estimates are too high… but the birth/death data is reliable, the domestic migration data also fits the available data, and the annual estimates are official Census numbers. So, it is what it is.

During WWII, Maine lost out to international migration (deployments) and domestic migration (wartime industry relocation). Post-war, Maine tended to have breakeven international migration, and negative domestic migration. Population growth came from the baby boom fairly exclusively duuring this time. But then in the 1970s, Maine got a wave of both international and domestic movers. By the 1980s, Maine was benefiting from robust domestic inflows.

But birth rates have steadily declined. During the great recession, deaths began to exceed births, even as migration was barely breakeven.

So let’s explore some of these trends. What’s going on with fertility?