pack-horsemen, blazing the way for the heavier forces quietly
biding their time in the rear--the Conestogas, the steamboat, the
canal boat, and, last and greatest of them all, the locomotive.

Through a long preliminary period the principal center of
interest was the Potomac Valley, towards whose strategic head
Virginia and Maryland, by river-improvement and road-building,
were directing their commercial routes in amiable rivalry for the
conquest of the Western trade. Suddenly out from the southern
region of the Middle Atlantic States went the Cumberland National
Road to the Ohio. New York instantly, in her zone, took up the
challenge and thrust her great Erie Canal across to the Great
Lakes. In rapid succession, Pennsylvania and Maryland and
Virginia, eager not to be outdone in winning the struggle for
Western trade, sent their canals into the Alleghanies toward the
Ohio.

It soon developed, however, that Baltimore, both powerful and
ambitious, was seriously handicapped. In order to retain her
commanding position as the metropolis of Western trade she was
compelled to resort to a new and untried method of transportation
which marks an era in American history.

It seems plain that the Southern rivals of New York City--
Philadelphia, Baltimore, and Alexandria--had relied for a while
on the deterring effect of a host of critics who warned all men
that a canal of such proportions as the Erie was not practicable,
that no State could bear the financial drain which its
construction would involve, that theories which had proved
practical on a small scale would fail in so large an undertaking,