Which mountain chain acted as a natural boundary between the 13 colonies and the Ohio river valley?

As a natural boundary between the French and 13 British colonies, the Appalachian Mountains acted. It would appear that both groups would stick to their own side, but an area called the Ohio Valley area was claimed by both the British and French. West of the Appalachians, surrounding the Ohio River across to the Mississippi River, was the Ohio Valley area.

the alfred thayer mahan award for literary achievement is awarded each year by the navy league of the united states. the award is named for an american naval historian and theorist, rear admiral alfred thayer mahan, united states navy who, through his writing, provided stimulus and guidance to those who share in the defense of the nation. presented since 1957, "this award for literary achievement is awarded to a u.s. navy officer, u.s. marine corps officer, enlisted service member, or civilian who has made a notable literary contribution that has advanced the knowledge of the importance of sea power in the united states."[1]