Conversation so far:
What is dirt research?
gathering masses of firsthand information and accumulating what he called "dirt" experience.
What kind of information was he gathering?
archival documents to understand the history of the fur trade.
When did he start?
Innis travelled extensively beginning in the summer of 1924.

Question: Where did he travel?
Self-contained rewrite: Where did Harold Innis travel beginning in the summer of 1924?