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

The idiom "along the line" likely originated in the United States during the early 20th century. Though it is not known exactly where it came from, people commonly use it in casual conversations to talk about a specific moment in time or a stage in a process where something happened or changed. This phrase is typically used when one is not sure about the exact when or where of a particular event or change.