According to this, there had been two parallel lines of development.

There were two parallel lines built in 1977 and 1987.

"It is as though they live along parallel lines that never meet."

Look for two parallel lines, say three to six feet apart.

The leaves have parallel lines on either side of the central vein.

Instead, they built a parallel line to Ripley, which opened in 1855.

On a chart, they should be two parallel lines with a large gap between them.

There were long, parallel lines carved into the floor and walls all around him.

"Never two parallel lines, if there is to be a dialogue."

The plants had been getting coal via a parallel line.