Push factors include war, famine, descrimination ect. in the native country of the migrant eg Irish people were pushed to emigrate to america and england during the Great Hunger (1845-1849)
pull factors include the promise of good job opportunities in america, hot climate, ect
The telegram was considered perhaps Britain's greatest intelligence coup of World War I and, coupled with American outrage over Germany's resumption of unrestricted submarine warfare, was the tipping point persuading the U.S. to join the war.