They closed the Mississippi River to all American commerce in 1784. This made it difficult for American farmers to get their goods to international markets. Spain would eventually allow Americans to use the river, but placed a tariff for the privilege. <span />
There are three main reasons for European Exploration. Them being for the sake of their economy, religion and glory. They wanted to improve their economy for instance by acquiring more spices, gold, and better and faster trading routes. Also, they really believed in the need to spread their religion, Christianity.