A long formation of lights across the lower Northern sky, flying straight and evenly spaced that lasted for several minutes.

We were at our cabin in the mountains and getting ready to leave. As we approached our car, I noticed in the northern sky, just above the tree line a string of lights flying in a straight line from West to East. They were evenly spaced and all going about the same speed. I would normally think it would be a satellite, but there were so many of them.
This "parade" or formation of lights lasted for several minutes, I would say at least 3 minutes. They faded and gradually disappeared as they headed East. There had to be over 100 "lights". Eventually they stopped, but it was a very consistent formation, a straight line of lights all flying across the sky (not falling like a meteor, or space debris) They were too far away to see any shape or color Although I am somewhat skeptical of UFO's, I don't disbelieve. This is definitely the first time I have ever made any type of report.
My background: I have a college education, am over 60 yrs old and do not drink alcohol or do drugs.