Turning points discussed earlier are a function of k, L1, and L2, as shown by
equation (13.5), and hence should only be interpreted from the viewpoint of how
urbanization affects national inequality, holding constant other factors. Since k,
L1,and L2 can all change independently of urbanization, the turning point is not
unique for each country. It can shift, either forward or backward, depending on
how urban inequality, rural inequality, and/or the urban–rural income gap change
and interact with each other.5 Therefore, a country’s national inequality may still
increase in the future, even if it has passed the turning point currently. In the case
of the PRC, for example, if urban inequality continues to rise and becomes higher
than rural inequality, shifting population from the rural to urban sectors may start
to increase within-group inequality, and whether national inequality increases or
decreases with urbanization will depend on the relative magnitude of the increase
in within-group inequality and decrease in between-group inequality.