The phrase "a common border" is correct and usable in written English.
It can be used to describe a boundary that is shared by two or more countries or regions.
Example: "The two countries have a common border that stretches for over 1,000 miles."
Alternatives: "shared border" or "mutual border".
We share a common border with another nation.
Somalia and Kenya have a common border of 800km, so our destinies are inextricably linked.
China and India have a common border and a history of conflict.
The Rev. Edward Mackiewicz, a Polish citizen, was stripped of his visa at a border crossing between Poland and Belarus, which shares a common border policy with Russia.
"We have put in place a common border without putting in place sufficient means to control this border," the French immigration minister, Eric Besson, acknowledged the other day.
"With a common border," says Ariel Sharon, leader of Israel's opposition, "the end of the existence of the Hashemite Kingdom is only a matter of time".
The Brazilian government is closely monitoring the situation in the Triple Frontier region, where Brazil, Argentina and Paraguay share a common border.
Third, EU states must focus on creating a common-border regime, coastguard and asylum agency rather than return to the era of the Berlin Wall.
But even if that were not so, Russia could still not risk angering China on a vital matter, not with a long common border and a huge and growing disproportion in population and non-nuclear military might.
Spatial dynamics seen within Switzerland might be mainly governed by internal processes because the other two neighbouring countries of Switzerland with a long common border, Germany and Italy, experienced only an extremely mild and late influenza season.
A condominium is a territory jointly administered by two or more countries, often (but not necessarily) a territory on the common border between the parties involved.
