he five years ending 1774 the West Indies received L6,748,095; the
thirteen continental colonies, L13,660,180.[42]

Imports from the continent also supported the carrying trade of Great
Britain, but not to an extent proportionate to those from the islands;
for many of the continental colonies were themselves large carriers.
The imports to them, being manufactured articles, less bulky than the
exports of the islands, also required less tonnage. The most marked
single difference between the West India communities and those of the
continent was that the latter, being distributed on a nearly north and
south line, with consequent great divergences of climate and products,
were essentially not homogeneous. What one had, another had not. Such
differences involve of course divergence of interests, with consequent
contentions and jealousies, the influence of which was felt most
painfully prior to the better Union of 1789, and never can wholly
cease to act; but, on the other hand, it tends also to promote
exchange of offices, where need and facility of transport combine to
make such exchange beneficial to both. That the intercourse between
the continental colonies required a tonnage equal to that employed
between them and the West Indies,--testified by the return of 1770
before quoted,[43]--shows the existence of conditions destined
inevitably to draw them together. The recognition of such mutual
dependence, when once attained, furthers the practice of mutual
concession for the purpose of combined action. Consequently, in the
protracted struggle between the centripetal and centrifugal forces in
North America, the former prevailed, though not till after long and
painful wavering.

While thus differing greatly among themselves in the nature of their
productions, and in their consequent wants, the continental colonists
as a whole had one common characteristic. Recent occupants of a new,
unimproved, and generally fertile country, they turned necessarily to
the cultivation of the soil as the most remunerative form of activity,
while for manufactured articles they depended mainly upon external
supplies, the furnishing of which Great Britain reserved to herself.
For these reasons they afforded the great market which they were to
her, and which by dint of habit and of interest they long continued to
be. But, while thus generally agricultural by force of circumstances,
the particular outward destinations of their surplus products varied.