Okay kiddo, have you ever been to a big, busy city like New York or Los Angeles? Well, imagine that there are lots and lots of cities in a country, but one of these cities is much bigger and more important than all the others. This city has more people, more businesses and more power. This concept is called urban primacy.
When a city is too big or too dominant, it can cause some problems, like all the wealth and resources going to that one city, while other cities are not able to develop as well. Also, everyone wants to move to the big city, which leads to overcrowding, pollution, and crime. So, it's important to have a balance and support other cities as well.
Just like when we play with our toys - we can't just play with the biggest one, we need to share and use all of the toys, so that everyone can have fun. This is what we want to do with cities too - make sure everyone has a chance to grow, develop and prosper!