Final answer:
George Pullman hired black men as porters to exploit cheap labor against the backdrop of the Great Migration and prevailing discriminatory labor practices.
Step-by-step explanation:
George Pullman decided to hire only black men as porters in his railroad cars primarily to exploit cheap labor. This practice took advantage of the socioeconomic conditions following the Great Migration, during which African American men were often relegated to menial jobs due to systemic racism and limited opportunities. The railroad industry was no exception, and black men found employment as porters, which was one of the few job prospects available to them. It was a common practice at the time for employers to hire African Americans for lower-paying, unskilled jobs, and Pullman was no different in seeking an economically advantageous solution for his company. This hiring practice was not aimed at promoting diversity, responding to a labor shortage, or as a means of social activism. Instead, it was a calculated business move that took advantage of the discriminatory labor practices of the era.