• Why do people migrate
• Push forces
• civil war
• environmental degradation
• unemployment or underemployment
• religious or ethnic persecution
• pull forces
• better economic opportunities
• better health services
• political freedom
• Total fertility rate (TFR)
• TFR- average number of children born per woman
• For population to remain the same, the TFR must be 2.1
• Higher than 2.1 population climbs
• lower than 2.1 population falls
• world TFR is 2.42