"Where? Certainly not in the part of the country where I live. Were
not standard 30 years ago or 40 years ago either. I haven't seen any
78" doors at HD, must be a custom order item. Sure you aren't talking
about mobile home or trailer doors?"

I said in my post that I had to order them. Now that I think about it,
I did order them at Lowes, but I could have ordered them at Home Depot
just the same. You have to go to the desk in the door area to order
them. They will not be in stock, even in the Home Depot is in a
neighborhood like mine where they would be in demand. And yes every
house in my neighborhood (built in 1950's) has 78 inch high door
everywhere.