Among the first things she said was that if the larger picture is considered, "we can see the development of communities on both sides of the United States-Canada border have been shaped by migration".
We often think of Canada as an immigrant country, and we know that many of those immigrants from Ireland, for example, eventually went to the United States. But what "pulled" them to go in the 1800s, after settling in Canada? No matter what their age, thousands just picked up everything and went to the States. Why?
There are many reasons for this migration to the States. Some of the more important ones are -
Economic - There were more job opportunities in the States. The people south of the border needed factory workers, lumbermen, and farmers - all the things that Canadians were willing to do for a living.
Some Canadians came back to Canada once the work was finished, but just as likely many stayed or moved on to greener pastures, so to speak.
Land Grants - Just as Canada did with people in Great Britain and Eastern Europe in the early 1800s, the States did the late 1800s - they sent out advertisements looking for people to move to a specific area and to take land grants.
Cluster Migration - When familles, co-workers, friends, and neighbours all moved together to an area to find work. In my case, one family member moved to the States, soon to be followed by another member, and then another member, and so on.
The reason they went to the States was strictly economic - but they went. They stayed, too, because they married there. They came to Canada to visit - but they stayed.
Where can you find these people today? What records would you look at to find them in the two countries of Canada and the United States?
The first place I would look at would be the Canadian Genealogy Centre website at http://www.collectionscanada.ca.
They have articles, diaries, and databases on immigration to Canada. To go along with that, I would suggest the website of the Ontario Archives http://www.archives.gov.on.ca.
Here, you will find that naturalization papers are available, immigration between Canada and the United States is discussed, and books on this subject have been transcribed.
In Canada, check the Our Roots website at Our Roots.
This is a very good site, as they have digitized hundreds of books about Canadian history, and are an excellent resource.
Another place to look is Cyndi's List for Canals, Rivers and Waterways.
She has 136 links to various places where you would expect to find people migrating - like the Erie and Panama Canals, pioneer wagon trails across Canada and the United States, and the Mormon, Ohio, and Oregon Migration Trails.
One last thing - don't forget to check city directories, Google Books, railway sites, and timelines of both Canada and the United States to establish when your family left, and where they settled.