The Law of the Primate City and the Rank-Size Rule

A country's leading city is always disproportionately large and exceptionally expressive of national capacity and feeling. The primate city is commonly at least twice as large as the next largest city and more than twice as significant. - Mark Jefferson, 1939

Geographer Mark Jefferson developed the law of the primate city to explain the phenomenon of huge cities that capture such a large proportion of a country's population as well as its economic activity. These primate cities are often, but not always, the capital cities of a country. An excellent example of a primate city is Paris, which truly represents and serves as the focus of France.

They dominate the country in influence and are the national focal-point. Their sheer size and activity becomes a strong pull factor, bringing additional residents to the city and causing the primate city to become even larger and more disproportional to smaller cities in the country. However, not every country has a primate city, as you'll see from the list below.

Some scholars define a primate city as one that is larger than the combined populations of the second and third ranked cities in a country. This definition does not represent true primacy, however, as the size of the first ranked city is not disproportionate to the second.

The law can be applied to smaller regions as well. For example, California's primate city is Los Angeles, with a metropolitan area population of 14.5 million, which is more than double the San Francisco metropolitan area of 6.3 million. Even counties can be examined with regard to the Law of the Primate City.

Examples of Countries With Primate Cities

• Paris (2.2 million) is definitely the focus of France while Marseilles has a population of 800,000.
• Similarly, the United Kingdom has London as its primate city (6.9 million) while the second largest city, Birmingham, is home to a mere one million people.
• Mexico City, Mexico (9.8 million in the city; 16.6 million in the metropolitan area) outshines Guadalajara (1.7 million).
• Bangkok is one of the most dominant primate cities in the world. It is 35 times as large as the second largest city of Chiang Mai., which is located in northern Thailand. Bangkok is the transportation and communication center of the country, as all railroad tracks, roads and airplane routes center on it. Bangkok is also the heart of the financial, commercial, educational, industrial and administrative activity within Thailand. Most importantly, Bangkok is the symbolic focus of the government, Monarchy and religion. Bangkok has a disproportionate share of the nations political, administrative, cultural, commercial and industrial institutions. However, the rest of the country is much stronger agriculturally, providing the food demands of the growing city. Bangkok has been unwilling to decentralize control in the past and as a result, there is a huge difference in welfare levels between Bangkok and the other regions, leading to instability and disunity. This has been caused by, and in turn causing, many people to move into the city, thinking that life will be better there for them. Many of these people end up in slums, and the women turn to prostitution. A large part of the money that they earn is sent to their parents and children left behind in the village.

Examples of Countries that Lack Primate Cities

• India's most populous city is Mumbai (formerly Bombay) with 9.9 million; second is Dehli with 7 million, third is Kolkata (formerly Calcutta) with 4.4 million, and fourth is Chennai (formerly Madras) with 3.8 million.
• China, Canada, Australia, and Brazil are additional examples of non-primate-city countries.
• Utilizing the metropolitan area population of urban areas in the United States, we find that the U.S. lacks a true primate city. With the New York City metropolitan area population at approximately 20.1 million, second ranked Los Angeles at 15.8 million, and even third ranked Chicago at 8.8 million, America lacks a primate city.

Rank-Size Rule

In 1949, George Zipf devised his theory of rank-size rule to explain the size cities in a country. He explained that the second and subsequently smaller cities should represent a proportion of the largest city. For example, if the largest city in a country contained one million citizens, Zipf stated that the second city would contain 1/2 as many as the first, or 500,000. The third would contain 1/3 or 333,333, the fourth would house 1/4 or 250,000, and so on, with the rank of the city representing the denominator in the fraction.

While some countries' urban hierarchy somewhat fits into Zipf's scheme, later geographers argued that his model should be seen as a probability model and that deviations are to be expected.