Because I know that the 49th parallel was decided as the boundary between Canada and the United States for Minnesota, North Dakota, Montana, Idaho, and Washington. Everything east of that, the border doesn't look nearly as smooth. So everything north of this line, Canada gets. Everything south goes to the United States.
That's cool, but also consider that Vancouver, BC today is one of Canada's most important cities along with Toronto and Montreal. Vancouver also happens to lie just barely north of the 49th parallel. It is strategically located on a peninsula that juts westward into the Pacific Ocean. This makes it an ideal center for trading with the United States and various Asian countries.
Everything in Canada east of Vancouver and west of Ontario is just landlocked land, for the most part. This geographically advantageous peninsula just happened to be a few miles above the 49th parallel north. So does that mean Canada simply got lucky with this piece of land? Or did Canada actually specifically choose the 49th so they could cede as much land as possible to the United States without losing where Vancouver would be?
I don't know if it could be considered luck or otherwise, but probably just happenstance. The Treaty of 1818 between the US and the UK and Ireland marked the border at the 49th parallel and was known as a convention respecting fisheries, boundary and the restoration of slaves. This happens only 10 years after Simon Fraser reached the mouth of what is now the Fraser River, and landed at the native village of Musqueam.
At that time, the area we now know as Vancouver was mostly a native fishing village (or villages). It's not even until 1824 that Hudson Bay Co. chief trader James McMillan arrived at the Fraser River, and three years later the first fort, Fort Langley, is under construction. By 1831, it's still naught more than a fishing village with salmon curing for commercial export with the help of native women. There isn't even a mission in this area until 1841! The area gets more attention in 1858 as gold seekers arrive, and in 1860 the first city in the area is incorporated: New Westminster.
All this to say, it would appear as though there wasn't a lot of foresight given into how advantageous this spot would be in the future (read: now). Logging doesn't even begin in earnest until the mid-to-late 1860s, and is just a faint shadow of what it became a hundred years later in the area. Consider then that Vancouver was still really just a logging town in '60s, and doesn't start to see massive growth for a few years yet. No one could have predicted this in 1818, so I'll have to go with luck. It most certainly would not have been seen as a particular place that was needed for anything other than maintaining a straight line along a parallel.
Please check out 1818 in the United Kingdom: Treaty of 1818 by LLC books and The Greater Vancouver Book edited by Chuck Davis.
Edit: I a word.