The American Southwest owes its expansion partly to the Spanish carreta. The carreta was a crudely constructed two wheeled wagon pulled by oxen. The design of the carreta, with its springless axles and peg construction, provided for a rough cargo ride to say the least.

The carreta's distinctive screeching wheels forewarned people of its arrival. "The wheels are never greased, and as they are driven along they make an unearthly sound..." wrote U. S. Attorney for the New Mexico territory William Watts Hart Davis in the 1850s. The driver feared if the wheels were oiled, that evil spirits would interfere with his trip, while screeching sounds scared them away.

There were many uses for the carreta. Women carried laundry to the river in them, and they were used to haul timber, trade goods, and supplies. The carts traveled over deeply grooved trails, so the very large wheel construction helped the carreta ride more smoothly. The carreta found its way with the Hispanic population to the Southwest, California, Colorado, Louisiana, and as far east as Kansas.