A primate city is the leading city in its country or region, disproportionately larger than any others in the urban hierarchy. A 'primate city distribution' has one very large city with many much smaller cities and towns, and no intermediate-sized urban centres, in contrast to the linear 'rank-size distribution'. The 'law of the primate city' was first proposed by the geographer Mark Jefferson in 1939. He defines a primate city as being "at least twice as large as the next largest city and more than twice as significant." A primate city is number one in its country in most aspects, like politics, economy, media, culture and universities.
Not all countries have primate cities, but in those that do, the rest of the country depends on it for cultural, economic, political, and major transportation needs. On the other hand, the primate city depends on the rest of the country as paying consumers of the cultural, economic, political and other services produced in the area.
The presence of a primate city in a country may indicate an imbalance in development – usually a progressive core, and a lagging periphery, on which the city depends for labor and other resources. However, the urban structure is not directly dependent on a country's level of economic development.
Many of the primate cities are increasing their percentage of their country's population. This can be because the number of traditional workers have been reduced because of mechanization in the manufacturing industry, agriculture, and other blue-collar industries, which are generally located throughout all of the country. At the same time, the number of educated employees in service business such as politics, economy, culture, media, and higher education has been rising, and those sectors are often located in the capital where the power and money is concentrated.
Among the best known examples of primate cities are alpha world cities such as Paris and by most measures London. Budapest, Dublin, and Vienna have also been described as primate cities. Bangkok has been called "the most primate city on earth", being forty times larger than Thailand's second city.