Here is a nice map of all of the main Presbyterian bodies in the USA. It shows the places of origin and the splits that have occured. This is a good resource for Presbyterians who have to try to explain where they are from and why their church was never connected with the PC (USA).
* The promoting of this map does not mean that I promote schism of any kind, nor does it justify why the Presbyterian churches are in such a state of chaos. Remember- the Lord prayed that we would be one as the Father and the Son are one. Much shame is on the Presbyterians for their schismatic ways.