Lee's Theory of Push and Pull Factors: push factors; that is, undesirable conditions in the sender population that make remaining at one’s current place of residence unattractive. They might include lack of jobs, housing, schooling, or other social amenities, and ethnic prejudice, difficult political conditions, or natural disasters. Pull factors, conditions that make a potential receiver population attractive, include perceived economic,
social, and political opportunities in a geographic area different from—but ordinarily close or adjacent to—one’s current place of residence
Social Network Theory: suggests that international migration is a well-organized activity that is managed by new immigrants and closely associated potential migrants related by family or kinship ties