Mark:
Is Shinnecock any better? (I recall driving around the eastern edge of Long Island one summer, roaming around SH and NGLA, and it seemed pretty narrow and congested, esp. at the height of the Hamptons season.)
Hard to say before it happens, but I think concerns about getting folks in and out of Erin Hills are a bit over-stated. Whistling Straits, which is near...a tavern...., used busses to simply bring folks in from Sheboygan, drop them off at the front gate, and shuttle them back. For those like me who opted for cars, there was plenty of parking and another shuttle system to get to the main gate. Seemed to work. I'd imagine a similar system for EHills, if they go there for the US Open.