Metros glue suburbs to cores with jobs and trains
A metropolitan area pairs a dense urban core with surrounding territories that share labor, commerce, and media—built-up or not, so long as ties bind tightly. Definitions wobble by country; a 2020 UN-agency effort tried to harmonize how the world counts them.
A metro can stretch across towns, counties, even national borders, as in Europe's eurodistricts. Its outer ring, often called the commuter belt, need not look urban at all; East Hampton at the far end of Long Island counts as part of metropolitan New York. The 2020 framework, agreed by the European Commission, FAO, UN-Habitat, the ILO, the OECD and the World Bank, calls the unit a functional urban area: a city plus every contiguous district where at least 15 percent of employed residents work in that city.
Usage still varies so much that one metro's population can differ by millions depending on the source. Metropolitan can also describe a county-level government sharing services between a city and its suburbs. A polycentric metro may contain several cores with no continuous development between them, since integration with a nucleus matters more than contiguous building. One proposed fix, the Urban Metric System, computes boundaries and centres from where people and jobs sit, and it has been trialled in Canada since 2018.
Johannesburg shows the gap between labels. Its greater metro held over 9.6 million people in 2011, against an urban area of about 7.9 million and a core city of under a million, while the metropolitan municipality governed nearly 5 million by 2016. Bangladesh has 12 city corporations, four of them inside metropolitan Dhaka.
Elsewhere the definitions multiply. China's 2019 guidelines describe a metropolitan area as the one-hour commuting zone around a dominant city within a larger city cluster. India treats any city over a million as metropolitan, and states can declare such areas for policing. Indonesia recognises ten, including Jakarta, Surabaya and Medan, while Pakistan has nine over a million, with Karachi the largest; Greater Tokyo was formerly the world's most populous.
Source: Metropolitan area
