"the route through which" is correct and can be used in written English.
It is used when you need to refer to a particular path or procedure that leads to a certain result. For example, "The route through which we must take is filled with many obstacles."
The window is a symbol of the middle passage, the route through which millions of Africans traveled, many of them dying, on their way to slavery in America.
Known as "the Boulevard," the corridor is a busy air bridge — the route through which Pakistan allows NATO aircraft access to Afghanistan.
But for now, lower bond yields and a stronger dollar are the route through which American spending will rise to counter European austerity.
The magnitude of marijuana's psychoactive effect depends on the THC level in the particular strain of plant, which parts of the plant are used, and the route through which the drug enters the body.
Ricciardi, a biologist, grew up on the banks of Lake Saint-Louis, which bulges out from the St .Lawrence River — the route through which the mussels metastasized to the Great Lakes.
Aristotle was a student of the natural world, and, unlike Plato, he assigned a much more important role to perception as the route through which humans gain access to that world.
Most of the major signaling pathways essential for human development — the routes through which information flows in cells — that were found to be mutated in cancer first were discovered in the fly.
Both sides would agree to cooperate in reducing the influence of the Taliban and Al Qaeda in Afghanistan; in combating drug trafficking; and in keeping open the routes through which energy flows to the world from the Persian Gulf.
This is achieved by analyzing the text of the report, the scale of the report's transmission, the routes through which the report was transmitted, and the individual narrators involved in its transmission.
How does context influence the routes through which reforms affect provider incentive environments and eventually motivation and performance?
In addition Blane et al. (2008) demonstrated with path analysis that depression is one of the routes through which health, specifically lung function limitation, affects quality of life.
