Consider the geographical location of the allies in relation to the central powers. what advantage might the allies have had?

Well first of all nobody invades Russia unless you are the Mongols. also, the English channel provided a physical barrier that has not been passed for almost 1000 years. the US was on the other side of the world so it was safe from bombing and such. The only man left out would be France which bordered Germany. 

“destroyers for bases agreement in the destroyers for bases agreement between the united states and the united kingdom on september 2, 1940, fifty caldwell , wickes, and clemson class us navy destroyers were transferred to the toyalbnavy from the united states navy in exchange for land rights on british possessions.” i hope this you .