Accompanying each episode, we'll have a post (or posts, if Brian blogs too) offering some more information and visuals about our topic. So this one will cover Episode 1. These posts probably won't be the most poetic writing, but hopefully they'll provide a little extra material for those interested.
So, here's some more information about the episode.
First off, we mentioned some changes in gross migration rates and the population-redistribution effect of migration. So here's some charts on that. First, a chart showing gross migration rates in the US, and a gross migration rate estimate for China. The source for the Chinese data is here. The average net migration rate estimate is based on a state-level migration database I've built going back to 1780, based on a plethora of sources. I regard it as very reliable. The gross migration rate after 1850 I regard as very reliable too. Before 1850, I do not regard it as being nearly as reliable. So treat those very high gross rates with some caution; they're based on very limited evidence.
As we discussed in the show, 1850s migration rates are at or below present-day rates of migration. However, the population impact of modern migration is much, much lower. In fact, recent migration has had the least population impact of any migration flows in American history. There is no time in our history when migration has had less impact on aggregate population. So, fun times to be a migration researcher.
It's possible that gross migration rates before 1850 were higher. Growing transportation networks, opening frontiers, and relatively low immigration during much of the period may have all contributed to forces pushing, pulling, and easing travel westward. As you can see, the population impact varied, but typically remained between 1.5% and 2% a year for most states.
The Chinese data is flawed, but the best I have on hand. As you can see, gross migration was far lower than in the US during the late 1990s. In the mid-2000s, Chinese domestic migration has been substantially greater than US domestic migration, but still below U.S. peaks in the 1950s, or potentially higher peaks in the 1810s and 1820s.
The chart above shows the "Migration Effectiveness Index," MEI, for the US and China in given periods. MEI measures the lopsidedness or unidirectionality of migration. It's calculated by dividing the absolute value of all regional net flows by the total gross migration flows. So if all regions have perfectly balanced migration (net flows in each region=0), then MEI is 0. But if all flows are unidirectional, i.e. everyone moves from Virginia to Alabama, and nobody moves from Alabama to Virginia, and that's true for every state-migration-pair, then MEI will be 200, because every migrant is counted twice, once leaving, once arriving.
Generally speaking, MEIs of over 50 are pretty large. If sustained for years on end, it's considered to be an extremely strong migration dynamic, reflecting an enduring imbalance in terms of push-pull factors or demographics. A value over 100 is considered quite extreme; that implies that "recipient regions" receive net inflows equal to more than 50% of gross inflows. That's extremely rare, especially for long periods of time.
As you can see, China's migration, despite being below or near US levels, is more unidirectional than US migration has ever been. This may be partly due to measurement error, as the Chinese government restricts internal migration. But this shows the key point made in the show.
Next topic: historic GDP and income. There are plenty of sources on this. You can find two specific papers I read here and here. The figure given of $50-$100 in GDP per capita I then multiply by some household size best guesses, for our ballpark of "a few hundred bucks a year" in average American income.
Conestoga wagon prices are here; I take this source at face value. If somebody knows a better estimate, I'm interested, but it's not essential. It's also worth noting here: in the show, I quoted my erroneous historical understanding that Conestoga wagons were used to settle the west. They probably were not. Most sources I've found suggest Conestoga-style wagons were no longer being produced after the 1840s, and 1850s at the latest. The Oregon trail wagons were of a different design, made much, much lighter to enable the long journey.
I've got some estimates of Kentucky historic population, 1760-1820. They're below. Now at some point, I'll do a big methodology post on my annual population and migration estimates. Not today. But below you can see my estimates of population, net migration, pop growth rates, and net migration rates.
I know the migration line is small, but you can see it rises a lot after 1790. That's almost certainly due to statehood, better roads, Wilderness Road improvements, the end of Native American violence in the state, and possibly some frontiersmen seeking escape from stronger government interference in the east. By 1820, however, Kentucky migration actually turns negative, as many Kentuckians move west or south. Consider two of the Commonwealth's most famous sons in this period: Jefferson Davis and Abraham Lincoln. Davis' father moves to Kentucky in 1793 and farms there. Davis is born in 1808. Then his family moved to Louisiana, then an even more newly-opened state, in 1811, then Mississippi to run a plantation in 1812.
Lincoln's grandfather moved to Kentucky in the 1780s, a very early frontiersman, but his father moved frequently. He settled down in 1808, and Lincoln is born in 1809, in Kentucky, less than 100 miles from Davis. But by 1814, Lincoln's father has lost a major land suit, forfeiting most of their farm, and so they move to Indiana. The land of opportunity in the 1780s, 1790s, and 1800s, by the 1810s and 1820s, Kentucky's position in the migratory life cycle had changed.
The above chart shows population growth, and that growth broken down into net migration and natural increase (births - deaths). Immigration, likely small, would also be included in natural increase here. My methodology creates some wonky years around the Censuses, but aside from those you can see that natural increase was fairly stable.
Migration, on the other hand, changed radically. Net migration was just 1 or 2% in the 1780s, but by the 1790s, Kentucky was adding 8% or 9% a year to its population through migration. That number declined from the 1800s and 1810s. No longer the frontier, by 1820 Kentucky was losing people, in no small part due to the sale of enslaved people into the south, a topic we'll discuss more in future episodes.
That's all the material I've got. The comments section is open. Leave me questions and criticisms and I'll respond as needed, including updating this post with more information.