Hallie uses the Colonial Parkway to enter Williamsburg. This route is actually out of her way, but it was always a favorite drive for my husband and I when we lived in the area and visited Williamsburg on a Sunday afternoon. The story talks about a change in acoustics when Hallie turns off to go into the city of Williamsburg. This is because the parkway's surface has tiny pebbles throughout, and it truly has a unique hum when you drive on it.
Construction of the Parkway started in the 1930's, and it was opened to the public in April 1957 (just a year before Hallie's next adventure in book 2 of the trilogy). It is 23 miles long, and it links the York River in Yorktown and the James River in Jamestown with a connection to Williamsburg in between. This is Virginia's historical triangle. It is a National Scenic Byway and All-American Road (only 1 of 31 total) in the United States. It is worth coming off the road more traveled to see the beauty surrounding it.
There was a more gruesome side of this natural museum. From 1986 to 1989 there were 8 people murdered (4 couples). Lots can be read about these horrible unsolved crimes. The thought was they were committed by a serial killer. The most recent post (July 2018) was made by a family member on his Facebook Page: Colonial Parkway Murders indicating the FBI has found DNA at 3 of the 4 murder sites. I truly hope it leads to solving these cases.