It seemed such a slender line to mark the boundary between death and safety.

They do not mark the boundary of what is actionable.

This line is important to some citizens because it marks the boundary of the "old city."

Every five miles a 3-foot high stone slab was placed to mark the boundary.

She stopped by the low stone wall that marked the boundary of the cliff top.

He played in the street, using cones and T-shirts to mark boundaries.

Although the Alps did not mark political boundaries, they often separated groups of people from one another.

Flares were used to mark the upper boundary of the track.

The post office marks the boundary between the two municipalities.

The bridge across the river roughly marks its northern boundary.