What are some comparisons between subway systems and elevated train systems?

It is the doctrine that the us had the right and duty to expand throughout north america. it just means they believed they had the right to expand westward and they did! they stated with the 13 colonies and then they kept moving gaining different territories throughout the years

The best title for the map above would be "earthquakes worldwide from 1900 - 2007". hope this

Some of the great contributes to advancement in the us were immigrants