Human trafficking can occur anywhere, but it is more likely to occur in places where people are in distress, not especially in any certain cities and towns.
The "travelling salesman problem" is the problem where you have to find the shortest route to visit each of several cities. Even if the distances between the cities are known, the solution is actuall quite complicated; a lot of different algorithms (methods) have been developed to optimize the problem under certain circumstances.
As of recent reports, the number one city often cited for human trafficking in the United States is Las Vegas, Nevada. The city's high tourism rate, large events, and transient population create an environment that can facilitate trafficking activities. Additionally, other cities like Atlanta and Miami also rank high due to similar factors. However, human trafficking is a global issue that affects many cities worldwide, making it difficult to pinpoint a single "number one" location.
In cities which have not taken steps to limit the problem - at the moment some of the Chinese cities have this problem.
New York City is currently ranked as the safest major city in the U.S., but during the 1970s until the mid-1990s, it had a serious crime problem.
London & cities all over the USA
nothing
You no longer have to go to certain cities to train certain weapon skills. You automatically know the skills that your class can use.
serious
mandates
mandates
It depends on where you are. There are certain areas of certain cities that I would be loathe to walk about at night.
Water