One of my old Steel books lists "Standard Lengths"
as follows; Light Rails 60 lbs and less 30 ft
with 10% of short lengths varying in even feet
down to 20 feet.
Heavy Rails Over 60 lbs ( 33 ft. with 10% of
( varying in even feet down to
( 25 feet.
(39 ft. with 11% of
( short lengths varying in
( even feet down to 25 feet.
These were mill run figures. For an additional
price, especially on large orders, the mill would
deliver exact lengths.
Some railroads had a certain length they preferred
and ordered accordingly. I believe the UP was one
that specified longer rail lengths. Since the NG was already built when they took over I doubt that any of the longer lengths were used there.
Most rails are considered to be 39 ft' and the
old counting of the rail joints for so many seconds to estimate speed was based on that length.
Jim