So, a long time ago, before there were airplanes and cars, people used big boats to travel and move things around the world. The United States, which is a big country in North America, has a lot of coastline, which means it has a lot of access to the ocean.
When the first people from Europe came to what is now the United States, they also came by boat. They also use boats to trade with other countries, like England and France.
In the 1800s, the United States started building bigger boats called "steamships." These ships were powered by steam, which was made by boiling water. These steamships could travel faster and carry more things than the old sailing ships.
The United States also had a big navy, which is a group of boats that protect the country. The navy helped keep the country safe during wars and also helped protect ships that were trading with other countries.
Over time, the maritime history of the United States became very important to the country's economy. Boats brought goods like food, clothing, and tools from other countries and took goods from the United States to sell to other countries.
Today, the United States is still a big maritime country with many ports and ships that travel all over the world.