Clopper Road is still there. It is a four lane road from Qince Orchard Boulevard to just past Rt. 118 where it returns to a two lane road. The end of Clopper Road is in a town called Boyds. From Rt. 118 to the end, the road is much like it was in 1969 through the mid-1980s.
In 1969, it really did seem idyllic in a way. Other than the farms and a few houses, there was nothing between Gaithersburg and Boyds other than the few stores and a few businesses in Germantown, and a gas station/country store at the corner of Clopper Road and Rt. 118.
Today, the road is built up from Quince Orchard Road to Seneca Creek, but the last mile or two is like it was back then. The concrete batch plant has been gone for a number of years, the old B&O railroad flag stop is now a MARC commuter rail stop for Boyds, but the rest of Clopper Road has been sold to housing developments. The trip from Rt. 118 to Boyds and to Dickerson beyond is still one of the nicest and peaceful drives in the Metropolitan area.