For two centuries, the main way to travel across America was the covered wagon. To construct a covered wagon, people built a wagon box of wood. Next they attached some hoop shaped slates. Finally, they stretched a canvas tent over the slats to cover the wagon. Of course, they needed something to pull their wagon. Popular choices were oxen, mules, or horses. Some covered wagon were boat-shaped and could float across streams. For safety, travelers, organized into groups that they called wagon trains. It took four to six months to travel between Missouri and the Pacific Ocean.