19
So much for that "massive area"
(pxscdn.com)
I chose this area because I thought that I'd have room to automate all the super early game mats and build my space elevator. Now I'm not so sure. Right now I have iron plates, iron rods, screws, wire, cable, and concrete automated with smelters ready to set up copper sheets the next time I play.
Pro tip, almost always build your factory in such a way that you can expand upwards. It's very rare to have a place on the map where you can't expand upwards. The exception is when you need to use fluids, then it's generally better to build horizontally.