North-South divide in Taiwan

North-South divide in Taiwan is made out of Taiwanese government's long-term over-investment in northern Taiwan that led to imbalance in economic development, political authority, medical access, educational supply, savings, and other kind of inequalities between northern and southern Taiwan. Because of this imbalances, southern Taiwanese often feel they're not fairly treated by the government.
In Taiwan, best schools and educational institutions supported by Taiwanese government are based in northern Taiwan. If you're southern Taiwanese wanting to study deeper, you will need to go to northern Taiwan. If you're an engineer or manager in a company, you will often need to go to northern Taiwan to update your knowledge.
From 1980 to 2000 in Taiwan, money that is paid, usually every month, to an employee was getting higher and higher leading to a tendency that companies moved out of Taiwan.
At the same time, many companies, who were able to earn more and thus pay more to their employees, started to grow in Taiwan. These companies made higher-value-added products and offered jobs needing college education not the kind of work that needs physical skills or strength in the past. Because Taiwan's higher educational institutions were near Taipei City, Taiwan, these "new companies" liked to go to northern Taiwan to run businesses.
Before 1980, Taiwan's main industries were farming, fishing, light industries and heavy industries. . Thanks to Japanese's policy that equally distributed resources for economic development, southern Taiwanese could find a job near their home in that time and even in the early time of the governance by KMT who succeeded Japanese to rule Taiwan since 1945. 
Birth, price, and population.
Since Taiwanese government invests everything in northern Taiwan, southern Taiwanese have had to go away from their home in southern Taiwan to northern Taiwan to find jobs. 
More and more Taiwanese move to northern Taiwan. However, northern Taiwan just has a little plain in the need of buildings. As a result, the price tags for people from southern Taiwan to buy a house in northern Taiwan to live become very expensive. 
Because of the expensive housing price, people in northern Taiwan have no choice but cut their desire to have babies. At the same time, southern Taiwanese don't have enough money to own a baby. So southern Taiwanese cut their desire to have babies, too. These lead to very low birth rate in Taiwan. After many southern Taiwanese moved to northern Taiwan, because they didn't own a house in northern Taiwan and were new to the environment, these movers' pockets generally not deep enough to pay a new house to start a family.
These lead to very low birth rate in Taiwan. Taiwan is one of the countries with the lowest brith rates in the world.
In southern Taiwan, the Skipped Generation Families/Grand-parenting Families are very often seen. In that, because many young children's parents have left to northern Taiwan to work. In the end, grand-parents become these young children's "real parents".