Can gmp file map be increases in size

[SteamTrain]

Is there a way to use a GMP map (Eastern USA) as a starting point which is X=319 Y=255 and increase it's map size? Say double or triple.

[arop]

It's not possible as far as I know

[Stoker]

I do not think you can increase a map size. But, you can make another map to the size you want. I have done it a couple of times. The hard part is filling in all of the detail- rivers can be a real PITA. WolverineMSU is the go-to guy for maps. If you can catch him I bet he will make a base map for you, then you just need to add the cities you want and landscape paint, rivers , etc.