What social, cultural, and geographic factors divided eighteenth-century colonists prior to the 1770s?
There are many factors which divided the British colonists in North America in the time before the 1770s. Let us look at some from the various categories you mention.
First, we can see that geography divided various colonists from one another. One way that geography did this was by creating very different environments that made different kinds of farming more feasible. The plantations of the South, for example, would not have been possible in the rocky soil and colder climate of New England. A second way that geography did this was by separating colonists on the coasts from those in the backwoods. This can be seen in the great differences between how colonists in the Piedmont of the South lived and how the settlers lived beyond the “fall line” where rivers were no longer navigable.
Second, we can see that cultural factors divided the colonists. One such social factor was religion. The Quakers, for example, were very culturally different than either the Anglicans in the South or the Puritans in the North. Their radically egalitarian attitudes divided them from the more hierarchical Anglicans while doctrines like that of the “inner light” divided them from the Puritans.
Third, we can see that social factors divided the colonists. One such social factor was the presence of large-scale slavery in the South. This made the South very different from the rest of the colonies in terms of the way that its economy and society were set up. Another social factor came from the fact that the Chesapeake area was settled by individuals, many of whom were indentured servants working for plantation owners while New England was settled by families. This made the New England colonies much more egalitarian and also much more settled and stable.
In all of these ways and more, the various colonies of British North America were divided. It would be very difficult to unite them to oppose the British and then, later on, to make a truly united country after independence.