From the LIGO website:

1. You won’t see any road signs marked “LIGO.”
2. Your cell phone or other direction finder most likely won’t recognize LIGO’s address or coordinates. We’ve hosted countless visitors who have reported great difficulty in making the drive to LIGO Hanford when they followed their phones’ directions.
3. Here’s the good news:  Google Maps recognizes LIGO Hanford if you enter LIGO Hanford Observatory 127124 North Route 10 as our location. Accept no substitutes! Occasionally people will add our location to online maps with unsuccessful results.
4. NOTE:  Google Maps sometimes shows road names in the vicinity of LIGO that don’t appear on signage.  WHAT YOU SHOULD KNOW: The turn off WA State Route 240 that takes you the final five miles to LIGO Hanford sits between mileposts 20 and 21 on SR 240 at the intersection with SR 225 (to Benton City). You’ll turn north off SR 240 to reach LIGO, not south. This is a right turn if you’re westbound on 240, and a left turn if you’re eastbound (toward Richland).
5. Google Maps directions from Spokane