A map can reveal alot of things. For instance, this map from Business Insider.
What the map reveals is where half of the GDP comes from. And according to the map, half of it comes from the top 23 metropolitan areas of the USA.
What this map does not show, however, is by what industries the GDP in the USA comes from. According to the information provided, the NYC-Newark-Jersey City metro has the highest GDP, $1.3 trillion. It makes sense as this is the largest metropolitan area in the nation. New York City is the major financial center of the USA. This metro area also has a major port industry, as alot of maritime trade takes place here. This is also a very expensive place to rent or buy a home. And manufacturing contributes a significant amount to the economy in this area. High technology is a growing industry in the NYC metropolitan area. The top 5 industries by GDP in the USA are: Real Estate/renting/leasing, government, finance/insurance, healthcare, and durable manufacturing.
Lets look at other metros, like Los Angeles, Chicago, and Houston. All of these cities are major trading centers, as all of them are on water. Houston is home to ConocoPhillips, the 4th largest corporation in the USA by revenue, as well as the 3rd largest energy company in the USA. Houston is a major oil-producing region, home to the Energy Corridor. Chicago is a major transportation and distribution center because of its geography. Insurance plays an important part of Chicago’s economy. Chicago is also a major financial center in the USA. It is home to the Chicago Stock Exchange. Although not as significant as it once was, manufacturing still plays a part in Chicago’s economy. Los Angeles is known for its entertainment industry. However lets not focus only there. 6 Fortune 500 companies make their home in Los Angeles. Occidental Petroleum, Health Net, Reliance Steel and Aluminium, AECOM(engineering firm), CBRE Group(real estate firm), and Tutor Perini Corporation(building contractor company). All represent major parts of the economy, such as the energy sector, manufacturing, health, and real estate. Los Angeles metropolitan area is the largest manufacturing center in the western USA.
The map shows which places contribute to 50% of the USA’s GDP. It does not say which industries are part of it or which industries those particular cities have. In order to understand geography, one has to look at the map, and then look beyond it.