During World War I, due to tensions between foreign countries, citizens of these foreign countries began to return to their native countries. As more immigrants began to leave there was a massive shortage of labor in the northern industries since during this time immigrants had dominated the work force in most northern factories and industries. However, this shortage was one of the main reasons for the Great Migration, labor and northern industry was needed for America's war effort and so, seeing their opportunity for a better paying jobs and a better quality of life, African Americans surged from the south to the north in hopes for a better lifestyle. Soon from almost every southern town hundreds of Africans Americans were migrating north. Even so, there were still many reasons as to why African Americans migrated north. Another major factor that caused many African Americans to migrate north was the Great Mississippi flood in 1927, this flood was the most destructive river flood in the history of the United States. This flood affected 10 states and destroyed many African Americans' homes and farms. With their source of living destroyed they were forced to migrate north to restart their life and get another source of income, which would be filling up the empty seats in the northern factories. Other reasons for African American migration north would be the boll weevil that had "ravaged" the cotton crops and destroyed one of the main industries in the south, with a lack of this cash crop many went north to earn money in another way. In addition, African Americans' quality of life in the South was extremely poor with staple things like food being too expensive, discrimination was also on the rise, with the number of lynchings increasing mainly because African Americans never received justice in southern courts. Finally, the last reason that caused many African Americans to travel north was the harsh and unfair treatment they had to face when working on tenant farms, which was one of the most common and one of the only jobs that was offered to African Americans in the South. One of the most common ways of migration from south to north was by train, African Americans' journey to the north would be paid by the northern industries, and these industries would later be repaid by the migrants out of their wages. Northern labor agents would also go south and hire African Americans as strikebreakers, giving another way for African Americans to go north. Many African Americans would leave early to get to their trains that would be taking them to new opportunities in the north, and  would also leave early to avoid southern officials who would arrest these migrants just to make sure they missed their train north. As the idea of migrating north got popular, hundreds of African Americans' rushed to the train station to buy tickets, so many people were trying to leave that special guards needed to be called to keep order in the crowded train stations, and the trains were even more packed with migrants traveling to popular, major cities like Chicago, New York, St.Louis, and Pittsburgh. Railroad platforms would be piled high with luggage and other personal belongings of migrants who were escaping the harsh society in the South. At first when migrants went north they found better paying jobs and a better quality of living, they found improved housing and upgraded working conditions. Letter written by African Americans to their relatives described how much better their life was in the North. There was more education and voting opportunities for African Americans in the North than when they were living in the south. More people were urging African Americans to migrate north and seeing the better opportunities there, African Americans left in large numbers to go north. However, with this massive increase in migrants, eventually led to the deterioration working conditions and the increase of Labor camps to keep up with the massive influx of migrants. As the migrant population grew the quality of life began decreasing and good housing became scarce as many African Americans' were forced to live in overcrowded, run down tenement houses. Housing for so many people became a serious problem and along with it a new form of discrimination that took the shape of segregation, though this was not as bad as the discrimination and violence they faced in the south. Disease like tuberculosis also became a serious problem since many migrants were getting sick due to the unhealthy living and working conditions. Lastly, race riots was another challenge that African Americans had to face in the north. Race riots were on the rise as whites felt African Americans were taking jobs meant for them, African American houses were bombed and set on fire to kick them out of neighborhoods where they were unwanted by whites. Many race riots became extremely violent, one of the most notable examples being the Tulsa Race Riot.