What development during the 1840s caused a sharp increase in immigration to america?

Were african-americans allowed to serve in the military in wwi? explain

The mass extermination of jews as part of the holocaust during world war ii caused the displacement of millions of jewish survivors. a large portion of them immigrated to which location? a. united states b. poland c. north africa d. palestine e. soviet union

Search america's open door policy with china beginning in 1899. explain how relations with the united states and china have changed and the effects of the open door policy on both countries.