Why is old Trafford called old Trafford?

Answer 1

The Stadium is called Old Trafford since it is built in an area called old Trafford.

Sir Matt Busby Way, Old Trafford, Manchester, M16 0RA

Generally speaking town areas are named old or new due to new development or a shift in the centre of the town. Its likely that Traffords town centre moved to a new location and thus Trafford became known as Old trafford to distinguish itself from the new location of the town centre (Which presumably was known as New Trafford for a while). There was no such place as Trafford, until Manchester divided in to ten Metropolitan Borough's in 1974

Answer 2

It's the nickname given to Old Trafford by Sir Bobby Charlton.