For every 100 nighttime residents: 90.2 by day in Nara, 87.6 in Saitama
In the 2020 census with unknown values imputed, Nara had 1,324,473 nighttime residents and a daytime population of 1,195,079. Saitama had 7,344,765 nighttime residents and 6,434,818 by day. With nighttime population set to 100, the daytime-to-nighttime ratios are 90.2 and 87.6.
Daytime population here is calculated by subtracting residents who travel outside the prefecture for work or school and adding people who come in from elsewhere. It is not simply a count of people employed locally; it also includes residents who do not commute or attend school. Both ratios fall below 100 because more people leave than enter for work or study.
Out-of-prefecture workers and students: 14.7% and 16.8% of all residents
The same census counts 195,323 Nara residents and 1,233,366 Saitama residents who work or study in another prefecture. These figures include both workers and students, not workers alone.
Divided by each prefecture's total resident population, the shares are 14.7% in Nara and 16.8% in Saitama. The denominator includes all residents, including children under 15, whether or not they work or study. These are therefore not the shares of employed people who commute out.
Nara is connected to the Osaka area, while Saitama's transport materials show a large flow toward Tokyo. But departures alone do not equal the difference between daytime and nighttime populations: people also travel in from other prefectures to work or study.
Work and schools remain within each prefecture, too
Saitama's transport materials also show that most residents who travel to work or school do so within the prefecture. Even with a large Tokyo-bound flow, daily destinations are not limited to Tokyo. Opportunities differ between areas near Tokyo and northern Saitama or Chichibu.
In Nara, travel along rail lines toward Osaka differs from travel in the southern mountains. The daytime-to-nighttime ratio describes the net effect of cross-border work and study trips. Looking at people who stay, leave and arrive gives a more concrete picture of local living areas than calling an entire prefecture a commuter town.