Why were Liaoning, Shandong, Shanghai and Sichuan the net inflow places from the founding of New China to the mid-1980s?

Liaoning is a heavy industry province in China. When New China was founded, the old industrial base declined, the employment rate declined and the population flowed out.

Shandong and Sichuan are populous provinces with abundant labor resources. In addition, the economy in this area is underdeveloped, with a large population and difficult employment.

Although Shanghai's economy is relatively good, due to war and other reasons, economic recession and unemployment certificates have increased.