Researching genealogy in New Brunswick is unique. In order to see the expansion of families and movements of connected groups, especially before the 1860s, it is better to look at the layout of the counties then any road.
There is perhaps no country in the world of the same extent that enjoys greater facilities of navigation than New Brunswick. All its large rivers are navigable for ships, and its smaller streams afford safe passage to boats and canoes. – Abraham Gesner [pg 71 http://www.archive.org/details/newbrunswickwithOOgesn
Waterways and portages were the main routes of travel even after the Great roads were created. But this is not the only way people appear to move.
A thing to remember when study any place with new and growing bureaucracy is that boundaries move. Even in the old world, such as, during the Industrial Revolution in England when populations shifted and grew, parish and other borders adapted. Look at the map here of Lancashire (from the Telegraph), an area heavily affected by the Industrial age, and see the changes that occurred in the mid-1700s to the mid-1800s.
In New Brunswick we saw changes quickly with the Loyalist’s love of bureaucracy. The first major one happened because of the communication lag between Halifax and Saint John (SJ). This could be a week to three given prevailing winds. On top the confusion of a government under pressure, it meant that decisions were just too long in the making. Communication problems left people living in poor conditions in SJ for weeks to years, waiting for promised land grants. This led to further troubles since many just struck off into the wilderness and squatted on the first piece of uninhabited land they found.
This delay led to the division of Nova Scotia into south and north, New Brunswick, down the middle of the Fundy. The next changes were the creation of counties and their civil parishes.
Here is Ganong’s map of the boundaries in 1786 along with the proposed changes. The parishes show us where the major populations were. The page also has a handy list of parishes and when they were created/altered.
This is import because if you were researching a family in Madawaska county in the 1881 census you will need to know to look for them in Victoria County in 1871. This was the last county to be created (1873.)
Knowing these changes happened and at least vaguely when is really most of the battle. I would recommend saving the New Brunswick counties page in your files for future reference. It is handy to have a print version for when visiting archives and libraries.
So people moved more than ever really expected. Using canoes, sails, and eventually steam or by sled on those same rivers in winter. But some never moved and had the maps shift around them.