How did the Spanish discourage American settlement in the west?

The railroads were granted land on each side of their tracks by the government to encourage their growth West. For every mile of track laid they received ownership of land on each side of the tracks. This was given or sold at bargain prices to settlers to encourage the growth of areas. The railroads were the primary mode of transpiration of goods and people until the paving of the highways in the 1920's and 1930's. The system of interstate highways marked the decline of the importance of the rails and opened the trucking system.