Borders are like invisible lines that separate different places. They show where one area starts and another ends. Just like how you have your own room and your brother or sister has their own room, countries also have their own "rooms" called borders.
In the case of the United States, it has borders with Canada and Mexico. So, imagine you have a yard and your neighbor's yard is just on the other side of a fence. That fence is like a border between your yards. Similarly, the United States has some land and Canada has some land, and there is a line that separates the two. This line is the border between the United States and Canada.
But what about the other border with Mexico? Well, picture another neighbor's yard, but this time it doesn't have a fence. It's just an open space between your yard and your neighbor's yard. In the case of the United States and Mexico, there is no physical fence or wall separating the two countries. However, there is still an imaginary line that shows where one country ends and the other begins, and that line is the border between the United States and Mexico.
The borders have rules that people need to follow when crossing from one country to another. Just like you need permission from your parents to go into your brother or sister's room, people need permission to go from one country to another. This is done by going through a special place called a border checkpoint, where officials check passports and other documents to make sure people are allowed to cross.
Sometimes, people try to cross the border without permission, and that is against the rules. It's important for officials to make sure everyone is safe and following the rules, just like your parents make sure you and your brother or sister are safe when you play outside in your yard.
So, borders are like lines that separate different places, and just like you have rules in your own home, countries have rules at their borders to keep everyone safe.