I heard that only 1% of the US population are farmers. That makes US just about the most efficient farming country in the history of mankind. US exports foods and use surplus for industrial purposes, such as turning corns into gasoline additive. In US, the problem is not about hunger, it is about obesity — the society suffers from having too much food.

Thousands of years ago, China enjoyed high farming efficiency. The industrial Chinese knew how to farm and was able to feed the whole country with a relatively small percentage of its population. That allowed the society to specialize. Instead of farming, people became artists, scientists, merchants, priests, soldiers, and, some, royalties. The civilization blossomed and the society became rich and complex. Just like US today.

A farming society is fundamentally sedentary. Clans became the dominant social structure in China. Since few thousands years ago, clans started to keep records on their members and formed the Chinese genealogy system. Last year, I discovered my own genealogy record that traced back to 60 some generations. I experienced a strangely strong bond between man and his ancestry. The magic about those ancestry records brought a sense of peace to my mind that I cannot explain. For the rest of my life, I will recognize that small town in FuJian (福建) as my hometown, even I may not visit it ever again.

The most important recorded events are migrations — 23 generations ago, an ancestor moved to that village and started the line that leads to me; few generations later, someone moved away to another town and started his own clan. Chinese have been free to migrate for many thousands of years. That's really how Han culture spread and made the middle kingdom.

In 1958, China government made it a law to record residential activities (中华人民共和国户口登记条例), such as migration, birth, death, and marriage. The law itself is mostly benign. It codified what Chinese clans have been doing for centuries and modernized it to include all people, clan-belonging or not.

The new country was destitute of foods after the war. The farming population and the foods they produced became the most precious commodity. The government chose to do three things: to regulate food consumption per capita, to preserve the farming labor, and to prevent the farmers from hoarding the foods they produced. It was hard time then. My hometown relatives told me near death stories. A bowl of rice will be savored to the last grain. Relatives in the rural areas smuggled foods in town to save them from starvation. If they got caught, they were likely to lose all rations and starve to death.

The country survived, thanks partially to the strict food regulations that based on those residential records, known as HuKou (户口). The precedence started a social structure layered on top of HuKou. Its foundational importance changed the direction of control 180 degrees. From then on, HuKou controls migration, instead of migration transfering HuKou. People cannot move unless the receiving municipality agreed to accept their HuKou. No HuKou, no jobs, no marriage, no kids. At least not legally.

Almost 50 years later, China is unraveling the knot of HuKou city by city, province by province. Every few months, a local government denounces HuKou with changes that invariably gives people more freedom to migrate. The first tier cities — Beijing and ShangHai in particular — are still slow to change. These are the wealthiest cities in China. HuKou keeps the floodgate of immigration shut lest social order collapsing, living standards deteriorating, or jobs lost to them.

The parallel of migrant people in Beijing with illegal immigrants in US is stunning.