After a two-hour delay to play in Williamsburg, Shin completed her opening round with a nine-under 62 to lead the way.
Thirty-three players were still on the River Course at Kingsmill Resort & Spa when darkness forced organisers to suspend play for the day.
Shin had done enough to open up a two-shot lead over Dewi Claire Schreefel of the Netherlands, who was at seven-under 64 when play was halted.
"My plan was no bogey. The rain helped make the greens softer, so I hit more aggressive on the back nine, too," Shin said.
Paula Creamer, Maria Hjorth, Azahara Munoz and Beatriz Recar were at six-under 65 and tied for third place.
Four more players were at 66.