Energy board spokeswoman Sarah Kiley says among the 2,131 applicants are many First Nations groups, municipalities from Edmonton to Vancouver, conservation groups and businesses.
One of the more unexpected applicants is the Washington State Department of Ecology, which is asking for a place at the hearings.
Under new federal rules, interveners will be limited to those who are directly affected by the project or can prove they have relevant information or expertise.
The $5.4-billion project will triple the capacity of the oil pipeline, which runs from Edmonton to the Vancouver area.
The board panel will review applications and decide who fits the criteria for taking part in hearings to be announced in mid-March.