The Security and Prosperity Partnership of North America (SPP) is like a big club where the leaders of Mexico, Canada and the United States made promises to work together to make things better for their countries. They called it "security" because they wanted to keep people safe from bad things like terrorism and "prosperity" because they wanted everyone to have more money and jobs.
They had meetings and talked about things they could do to help each other out. They talked about things like shipping goods between the countries faster and making it easier for people to travel back and forth. They also talked about sharing information to help stop crime and make it safer for everyone.
Some people didn't like the SPP because they thought it might take away their jobs or make their countries less independent. Others thought it was a good idea because it would help create jobs and make their countries safer.
In the end, the SPP didn't last very long because the leaders of the countries stopped meeting and talking about it. But some of the ideas they talked about are still being used today to help make trade and travel between the countries easier and safer.