The answer to go in the blank would be ''hobbs''.
Railroad expansion allowed Native American hunters to sell bison meat and hides at higher rates than before.
Railroad expansion brought U.S. settlers in contact with bison, drastically reducing the population of this food source.
Westward migration of U.S. settlers increased the number of farms, causing a supplementation of bison meat with grains.
Westward migration of slave-owning settlers diminished the demand for bison as a beast of burden, causing the bison population to increase.
The main way in which the rise of labor unions shaped relations among workers, big business, and government is that they gave far more power to the workers, who were able to pressure their companies into giving them better hours and working conditions--often with the help of the government.
Rundstedt had ordered the panzer units to halt, concerned about the vulnerability of his flanks and the question of supply to his forward troops. He was also concerned that the marshy ground around Dunkirk would prove unsuitable for tanks and he wished to conserve them for later operations (in some units, tank losses were 30–50 percent). Hitler was also apprehensive, and on a visit to Army Group A headquarters on 24 May, he endorsed the order.
