Here are 12 different state borders across the world - from the walled to the wonderful:
1. The US-Mexico border
670 miles of the US-Mexican border is marked by a metal fence.
Built in accordance to President George W. Bush`s 2006 Secure Fence Act, this cost the US government around £1.6 billion.
Trump`s proposal is to build a wall along the entire border - which is 2,000 miles long.
2. The Argentina-Paraguay-Brazil border
On the left is Argentina, the right Brazil and at the cross bar of this watery T-junction is Paraguay - it is known as the "Triple Frontier".
The United States has claimed the Paraguayan side near the triple border has played host to various Islamic terror groups including Hezbollah.
3. The Austria-Hungary-Slovakia border
All three countries have introduced strict border controls as a result of the thousands of migrants trying to make it through to Western Europe and the European Union.
The three sides of the table in the middle of the field have a flag representing each of the three countries.
4. The Egypt-Israel border
The Israelis have been building a fence along the border with Egypt, who have agreed as long as the barrier is built on Israeli soil.
Earlier this month, both Egyptian and Israeli militaries increased their presence on the border after a series of attacks on both Egyptian and Israeli targets by an IS-allied group from Sinai in Egypt.
The two countries have been working in co-ordination to fight this new threat, according to Bloomberg.
5. The Lithuania-Belarus border
This month, both Lithuania and Belarus were forced to hire more customs officials after being overwhelmed by the number of trucks attempting to cross the border.
This sudden surge of trucks is due to the breaking down of a border agreement between Russia and Poland.
This 421-mile border marks the outer border of the European Union.
6. The Poland-Ukraine border
This is the most crossed Eastern border of the European Union.
Relations between the west and Russia have soured after Russia annexed Crimea from Ukraine.
There is widespread support in Ukraine to apply to join the European Union.
7. The Macau-China border
While Mainland China is controls for Macau island`s defence policy and foreign relations.
The former Portuguese colony has its own legal system, police, monetary system, customs and immigration policy.
It also makes an interesting challenge for motorists. Drivers drive on the right hand side of the road in mainland China, and on the left in Macau.
8. The Netherlands-Belgium border (In Barle-Nassau)
This is the town of Baarle-Nassau in the Southern Netherlands is a patchwork of Belgian and Dutch enclaves.
To aid visitors to the town, the maze of border lines are marked on all streets.
This is due to a series of complex medieval treaties, sales and land swaps between the Lords of Breda and the Dukes of Brabant dating back to the 12th century.
9. The Spain-Portugal border
This is the only border in the world which you can cross using a zipline.
Visitors can clip on in Salucar de Guadiana in Andalucia, Spain and land across the Guiana river in Alcoutim, Portugal.
