A pass is a gap, or break, in high, rugged terrain such as a mountain ridge. A pass forms when a glacier or stream erodes, or wears away, the land between areas of higher terrain. Passes often provide the easiest routes for people to travel across steep mountain ranges. For this reason, they have played an important role throughout human history in migration, trade, and settlement.

Most passes are flat at their summits and have the shape of a saddle. They can consist of very short, steep summits, or expansive valleys that stretch for kilometers. Often, passes sit just above the source of a river fed by precipitation and snowmelt.

Passes are good places to build settlements or defensive outposts because they are usually the only flat land in a mountainous area. This vantage point also makes a pass an easier location to defend against threats or enemies.

In some parts of the world, passes connect different cultures that are separated by the mountains between them. The Khyber Pass, which connects Pakistan and Afghanistan in the Hindu Kush mountains, has served as a key trade route between Central Asia and South Asia for thousands of years. Today, it is the route between the modern cities of Kabul, Afghanistan and Peshawar, Pakistan.

"Pass" may also refer to a channel, or deeper part of a body of water, that allows passage through an otherwise shallow waterway.

pass
Hikers take a pass at Kneeknocker Pass.

Mysterious Pass
Hannibal (247-183 BCE) completed one of the most legendary crossings of the French Alps during the Second Punic War (218-203 BCE). Hannibal was from North Africa, the modern-day city of Carthage, Tunisia. He led not only his troops through the Alps, a formidable mountain range, but a number of war elephants as well. However, there is no record of which pass Hannibal used to cross the Alps. The subject remains intensely debated by historians.

Noun

waterway between two relatively close land masses.

consist
Verb

to be made of.

culture
Noun

learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.

debate
Verb

to argue or disagree in a formal setting.

defensive
Noun

resisting attack.

elephant
Noun

large mammal with a long trunk, native to Africa and Asia.

erode
Verb

to wear away.

formidable
Adjective

intimidating, or causing fear or hesitation due to difficulty.

Noun

mass of ice that moves slowly over land.

Noun

(247-183 BCE) general of the Carthaginian Empire.

Khyber Pass
Noun

gap in the Hindu Kush mountains linking Pakistan and Afghanistan.

legendary
Adjective

famous, heroic, or celebrated.

migration
Noun

movement of a group of people or animals from one place to another.

mountain
Noun

landmass that forms as tectonic plates interact with each other.

Noun

gap or break in rugged terrain, such as a mountain ridge.

Noun

all forms in which water falls to Earth from the atmosphere.

Noun

large stream of flowing fresh water.

rugged
Adjective

having an irregular or jagged surface.

saddle
Noun

seat for a rider on a horse.

Second Punic War
Noun

(218-201 BCE) armed conflict between the Carthaginian Empire and the Roman Republic.

settlement
Noun

community or village.

snowmelt
Noun

water supplied by snow.

Noun

beginning of a stream, river, or other flow of water.

Noun

body of flowing water.

summit
Noun

highest point of a mountain.

terrain
Noun

topographic features of an area.

trade
Noun

buying, selling, or exchanging of goods and services.

trade route
Noun

path followed by merchants or explorers to exchange goods and services.

valley
Noun

depression in the Earth between hills.

vantage
Noun

position or outlook.