You might know that Japan's population has been declining. However, if you've never look into the details, you might have just assumed that the population has been decreasing somewhat uniformly across the country like this:
This is not the case.
If we examine changes in each of the 47 prefectures, we can see that most prefectures are seeing a decline in population, but that a few prefectures are still seeing an increase in population:
Although most prefectures have a negative change in population, if we compare the absolute values of the changes, the change in Tokyo is 2.85 times of the prefecture with the 2nd largest change (Hokkaido).
This increase in the Tokyo population is known as 東京一極集中 or the centralization of population in Tokyo.
This is a well-known and widely discussed topic, but it doesn't receive as much attention outside of Japan, as evident in the small number of supported languages on Wikipedia—Japanese, Chinese and Scottish Gaelic1.
However, as shown in the bar graph, Tokyo is not the only prefecture seeing an increase in population. Where exactly are people moving from to these prefectures?
The following maps use data from 2020, so it does not match the years from the bar graph above (which only had data up to 2015). However, the overall trends should be similar.
Aichi is where Nagoya, the largest city in the region, is located. It's also home to Toyota, so many companies in the car industry are located there.
We can see that there are many people moving to Shiga from Kyoto and Osaka.
According to suumo, Shiga's population was increased by making it more convenient to travel to Kyoto and Osaka. They did this by building new train stations and roads, attracting universities and research facilities, etc.
Nationally, the population is centered in Tokyo, but in the Kyushu region, the population is centered in Fukuoka.
Fukuoka has good access to the rest of Kyushu by train. Fukuoka Airport is also extremely close to the center of Fukuoka:
The domestic terminal is connected to the city by the Fukuoka City Subway, and a subway from the airport to the business district takes less than ten minutes. (Wikipedia)
People move to Okinawa from many areas of Japan, but they also have a high birth rate compared to the other prefectures:
By prefecture, southernmost Okinawa recorded the highest total fertility rate at 1.82 and was the only one of the country's 47 prefectures to see more births than deaths.
Given the importance of Tokyo, I was thinking that there might a large number of people moving to Tokyo from other regions of the country.
However, the same pattern can be seen with Tokyo as well, with the most people moving to Tokyo from Kanagawa, Saitama, and Chiba.
I thought that this might be a result of COVID, but similar numbers can be seen in 2019.
This makes sense considering that many residents of those nearby prefectures work or study in Tokyo. If we look at where people moving to Kanagawa, Saitama, and Chiba, we can see that it is mostly from Tokyo.
Therefore, many people who work in Tokyo probably move between these prefectures in the Kanto area.
Tokyo is the center of Japan with many companies and universities, so it's natural that people continue moving to the Tokyo area in pursuit of opportunities. 55% of publicly listed company were headquartered in Tokyo, 11% in Osaka, and 6% in Aichi, even though they only make up 3% of the land.
1: Language support on Wikipedia doesn't necessarily demonstrate how much people in a particular country are interested in a topic, but I'm amused that there's a Scottish Gaelic page without English support. I'm also impressed (but not surprised) by the Chinese support.
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