Natural Reasons

• Certain weather patterns, such as droughts or floods, affect the growth of crops, which in turn impact different groups of people within a country. Farmers often lose their source of income when their crops are flooded or cannot grow properly due to droughts, and they move to a new place to gain employment opportunities. When the amount of food in an area becomes scarce, people often do not have regular access to food, which causes them to migrate to other areas. During the Irish Potato Famine, which occurred from around 1845 to 1855, about 1.5 million people emigrated to the U.S. because of the lack of food in the country resulting from fungi killing potato crops. In the United U.S. in the 1930s, during the "Dust Bowl," massive droughts affected wheat and cotton crops in states such as Texas, Oklahoma, Arkansas and Missouri, and many people moved out to California and other western states because of poverty and joblessness.
  
  

Political Reasons

• Political decisions and consequences, including wars, can lead to mass starvation, which in turn can cause migration. Wars, especially civil wars, often cause harm to farmland, which in turn leads to a lack of food within a country. A scarcity of resources means that many people, especially the lower classes, do not have regular access to essential items, including healthy food, clothing and homes; they often have to live in harsh conditions with little food. Due to the war in Iraq, many Iraqi people were jobless and in poverty, which has caused them to move to other countries, such as Jordon, Syria and Lebanon, in search of better opportunities.
  
  

Family Reasons

• Large groups of people often move to other countries or cities to support their families when they are unable to find jobs in the city or country in which they reside. Sometimes one or more members of a family emigrate to another country for work and send money back to their families. They may live in the other country permanently or for a short time to work in certain industries, such as agricultural, railroad or construction industries. Since the 1920s, large numbers of people have emigrated from Mexico to get higher paying jobs so that their families can have access to better food, shelter, health care and other necessary items and services.
  
  

External Reasons

• Groups of people often emigrate to another area because the country, city or state is seen as offering better economic opportunities than their home countries. A place can develop a reputation as being an area with more well-paying jobs than others. From around the mid-1600s until today, the U.S. has been seen as a country where people can become prosperous and flee poor economic situations to find better opportunities. People from a variety of European countries, including Ireland, Great Britain, China, Germany, France and Poland, have emigrated to the U.S. during different periods of history, starting during the Colonial Era. An influx of immigrants came to the U.S. from Asian countries, such as China, during the 1850s due to the "California Gold Rush."