Today I am reading an Algorithms textbook. The author, in order to explain the shortest path between two vertices in a graph, gives an example in the real world:
At one time, there was a speed trap on I-70 just east of the Indiana/Ohio border, but only for eastbound traffic.
In order to understand this sentence, I used Google Maps to find the site of Indiana and Ohio. I found that they have only one common border. And I think this border is an abstract line. So I can't understand what "east of the Indiana/Ohio border" means... Does the author mean "east of the common border"? It's in Ohio state. Why not say "in Ohio state" directly?