There is no open frontier with optimistic cowboys on his horizon.

During the first period, the open frontier made it possible for Americans to live in ways that became impossible for their descendants.

The days when Internet radio broadcasting was a wide open frontier are over.

A. Well, I think people feel the need for a continued existence of an open frontier.

But on the wide open frontier of the largest country on earth, the distance was considerably farther almost fourteen hundred miles.

It is a classic military problem: how do you defend a long open frontier against continual probing attacks?

Jefferson left the fourth side of the Lawn unbuilt, as a kind of open frontier to the future.

The Soviet Union, with its estimated 600,000 or more personal computers, has been an open frontier of software piracy.

There is no point in one country having much stricter regulations in a single market with open frontiers.

As EU economic integration and open frontiers increased, cooperation on public health issues became more important.