Double running stitch has been termed Holbein stitch for this reason. If the pattern wasn't quite reversible, the outside still looked great, and afforded much more freedom for the embroiderer to experiment and add little bits of stitches to darken the shading of the stitches. This type of embroidery was used on skirts, sleeves, and the edges of sheets and pillows, since the back wasn't in view. Lace was very highly prized and extremely expensive and I've heard it said that this was an acceptable substitute. I don't have any information on exactly when blackwork made it to America, so this is a matter of speculation.
Examples are very hard to come by.
Today, our contemporary expert is, arguably, since someone always wants to argue, Jack Robinson. He spent years studying and perfecting his technique in blackwork and received commendation in 1993 from The Worshipful Company of Broderers and The Embroiderers' Guild for his work. It is my understanding that he no longer does blackwork, but has moved on to goldwork. Try a sampler. OH the mind boggles.