After Ohio and Pennsylvania, oil production shifted to Texas and California and then, when people found it tougher to find oil onshore they tried offshore.
There is nothing different with newer technologies like hydraulic fracturing, directional drilling, and advanced imagine.
We aren't at peak oil because extracting oil always has been heavily dependent on technology.
Here's what the peak oil chart for the U.S. looks like today: https://en.wikipedia.org/wiki/Peak_oil#/media/File:Hubbert_U...