"down the line" の定義と意味

What is the origin of the idiom "down the line" and when to use it?

The idiom "down the line" likely originated from the railroad industry, referring to the direction away from the starting point along the tracks. Over time, its usage expanded to convey the idea of progression or movement from one point to another, either physically or metaphorically, often implying a later point in time or in the future.