The Atlas Obscura's US-Canada Border Slash, says:
The Slash was initially deforested for the sole purpose of, according to the IBC, making sure that the "average person… knows they are on the border." It all started in the 1800s, when the US-Canada border line was set at the 49th parallel. The Slash was cut and over 8,000 original border markers were laid down, most of which are still standing along The Slash to this day. Unfortunately, there was no GPS system at the time, so the border markers were inadvertently placed in a zig-zaggy fashion, straying north or south of the official 49th parallel border by an average of 295 feet. The lack of sufficient cartography also led to irregular border cutoffs such as Point Roberts and the Northwest Angle.
Question: Was there a particular need to "mak(e) sure that the 'average person… knows they are on the border'" that led to the slash, perhaps a dispute due to an ambiguity, or a treaty that required it? Or was this just a common-sense move who's time had come? Where there any particular immediate political or economic benefits to its implementation?