B1
the line that divides one country from another
Dictionary examples:
I accidentally walked across the border while looking at my phone. Oops! (0.0)
The border guard asked me, 'Why did you bring a rubber duck?' (0.0)
The chicken crossed the border to prove it wasn't chicken. (0.0)
Were you stopped at the border? (14.6)
The train crosses the border between the US and Canada near Buffalo, NY. (33.0)