Traffic jam and cities, it seems, go hand in hand. Everyone complains about being stuck in traffic; but, like the weather, no one seems to do anything about it. In particular, traffic engineers, transportation planners, and public officials responsible for transportation systems in large cities are frequently criticized for failing to solve traffic jam.But is traffic jam a sign of failure? Long queues at restaurants or theater box offices are seen as signs of success. Should transportation systems be viewed any differently? I think we should recognize that traffic jam is an unpreventable by-product of successful cities, and view the “traffic problem” in a different light.Cities exist because they promote social interactions and economic transactions. Traffic jam occurs where there are lots of people but limited spaces. Culturally and economically successful cities have the worst traffic problems, while decaying cities don’t have much traffic. New York and Los Angeles are America’s most crowded cities. But if you want access to major brokerage houses (经纪行), you will find them easier to reach in crowded New York than in any other large cities. And if your firm needs access to post-production film editors or satellite-guidance engineers, you will reach them more quickly through the crowded freeways of LA than through less crowded roads elsewhere.Despite traffic jam, a larger number and wider variety of social interactions and economic transactions can be made perfect in large, crowded cities than elsewhere. Seen in this light, traffic jam is an unfortunate consequence of prosperity, not a cause of economic decline and urban decay. So while we can consider traffic jam as increasing costs on the areas of big cities, the costs of inaccessibility (交通不便) in uncrowded places are almost certainly greater.There is no doubt that traffic jam brings the terrible economic and environmental damage in places like Bangkok, Jakarta, and Lagos. But mobility is far higher and traffic jam levels are far lower here in the U.S., even in our most crowded cities. That’s why, for now, we don’t see people and capital streaming out of San Francisco and Chicago, heading for cities like California, and Illinois.We can conclude from the first paragraph that_____________.