The boundary marked the end of the wilderness, and the beginning of America's Manifest Destiny.

This boundary marks the start of the Cenozoic era.

The boundary of the ancient woods marks the county boundary between Lincolnshire and Nottinghamshire.

Its northern boundary (Roosevelt Road) marks the end of consecutively named east-west streets.

She had laid out a map of the world, boundaries between the ten regions clearly marked.

The boundary between allowing to die and active medical killing marks a moral Rubicon.

This boundary marks the extent of the planned development.

The boundaries of the largest divisions--the eras mark the greatest events.

The column entered North Ulfland, the boundary marked only by a cairn beside the road.

Like jagged wounds, the boundaries mark histories of brutal violence.