AP HUGS Major VOCAB

Stimulus diffusion

Definition: An idea spreads, but people modify it as it moves to new places.
Example: McDonald’s in India serves chicken and vegetarian options instead of beef.

Contagious diffusion

Definition: An idea spreads rapidly and evenly through a population, usually through direct contact.
Example: A viral TikTok trend spreading quickly among students.

Hierarchical diffusion

Definition: An idea spreads from important people or major cities first, then to smaller places.
Example: A new smartphone is released in major global cities first, then spreads to smaller towns.

Relocation diffusion

Definition: An idea spreads when people physically move and bring it with them.
Example: Immigrants bringing their language and food to a new country.

Reverse hierarchical diffusion

Definition: An idea spreads from smaller or less important places to larger or more important ones.
Example: A fashion trend starting with teenagers or street style and later being adopted by major designers.

Expansion diffusion (umbrella term)

Definition: An idea spreads outward from its origin while staying strong in the original location.
Example: Christianity spreading globally while remaining strong in Europe.

Edge City

Definition: A large concentration of businesses, offices, and shopping outside the traditional CBD, often near highways or suburbs.
Example: Tysons Corner, Virginia (near Washington, D.C.)

Exurbs

Definition: Areas beyond the suburbs where people live in rural-like settings but still commute to the city for work.
Example: Towns outside Atlanta like Braselton or further rural counties where commuters travel into the metro area

Boom Burbs

Definition: Fast-growing suburbs on the edge of a metropolitan area, usually with rapid population and housing growth.
Example: Frisco, Texas near Dallas

Arithmetic Density

Definition: Total population divided by total land area.
What it shows: Overall crowding of a place (very general).
Example: A country with 50 million people and 500,000 km² → 100 people/km².

Physiological Density

Definition: Total population divided by arable (farmable) land.
What it shows: Pressure on land that can actually grow food.
Example: Egypt has high physiological density because most land is desert, so people are concentrated on small fertile areas.

Agricultural Density

Definition: Number of farmers divided by arable land.
What it shows: Level of development and farming efficiency.
Example: Developing countries often have high agricultural density because more people are needed to farm the land manually.

Physical (Natural) Boundary

Definition: A boundary based on natural features like mountains, rivers, or deserts.
Example: Andes Mountains between Chile and Argentina.

Geometric Boundary

Definition: A boundary drawn using straight lines or arcs, not based on physical or cultural features.
Example: The 49th parallel between the United States and Canada.

Cultural Boundary

Definition: A boundary based on cultural differences like language, religion, or ethnicity.
Example: India–Pakistan border based on religious differences (Hindu vs Muslim populations).

Superimposed Boundary

Definition: A boundary forced onto an area by outside powers, ignoring existing cultural or ethnic groups.
Example: Colonial borders in Africa drawn during European colonization.

subsequent Boundary

Definition: A boundary forced onto an area by outside powers, ignoring existing cultural or ethnic groups.
Example: Colonial borders in Africa drawn during European colonization.

Consequent Boundary

Definition: A boundary created to separate different cultural groups that already existed in an area.
Example: India–Pakistan partition border (1947).

Relic Boundary

Definition: A former boundary that no longer functions politically but still exists historically or culturally.
Example: The Berlin Wall (no longer exists but still significant historically).

Concentric Zone Model ( Burgess)

• The city is organized in concentric rings around a central business district (CBD).

• Lower-income populations are located near the center due to proximity to industrial jobs and lower land values.

• Wealthier populations live farther from the CBD where land is more desirable.

• This model reflects early industrial cities such as Chicago.

Sector Model (Homer Hoyt)

• Urban land use develops in wedge-shaped sectors extending outward from the CBD.

• Transportation routes influence the location of residential and industrial areas.

• High-income housing develops along desirable corridors.

• This results in patterns shaped by accessibility and transportation.

Multiple Nuclei Model (Chauncy Harris & Edward Ullman)

• Cities develop with multiple centers rather than a single CBD.

• Different activities cluster in separate nodes based on land use needs.

• Examples include business districts, industrial parks, and shopping areas.

• This reflects modern urban development and decentralization.

Latin American Model (Ernest Griffin & Larry Ford)

• The model includes a central CBD with a spine of commercial and elite residential development.

• Wealthy populations live near the center along the spine.

• Poorer populations are located on the periphery of the city.

• Peripheral areas often include informal settlements due to rapid urbanization.

African City Model (Harm de Blij)

• The model includes multiple CBDs such as a colonial CBD, traditional CBD, and market zone.

• Urban structure reflects the impact of colonial history.

• Ethnic and cultural groups influence land use patterns.

• Economic activities are often separated by these groups.

Southeast Asian Model (T. G. McGee)

• The model lacks a single dominant CBD.

• Cities contain multiple commercial centers.

• Port zones play a major role in economic activity.

• Land use is mixed with residential and commercial areas combine

Galactic City Model (Larry Ford)

• Urban development expands outward along highways.

• Edge cities form outside the traditional CBD.

• Economic activity is decentralized across suburban areas.

• This reflects a car-dependent urban structure.

POPULATION PYRAMID INTERPRETATION

1. Wide base

A wide base shows a high birth rate.
This indicates rapid population growth.
Common in developing countries.
Think: lots of children.

2. Narrow base

A narrow base shows a low birth rate.
This indicates slow or negative population growth.
Common in developed countries.
Think: fewer children.

3. Wide middle (working-age bulge)

A wide middle shows a large working-age population.
This can indicate economic growth or a past population boom.
Think: many working adults.

4. Wide top (older population)

A wide top shows high life expectancy.
This indicates an aging population.
Think: more elderly people.

URBAN SUSTAINABILITY

• Definition: reduce environmental impact + long-term city health

• Public transport → less cars → less pollution

• Green spaces → better air → less heat island effect

• High-density housing → less sprawl

• Mixed-use zoning → closer jobs/services → less commuting

• Result: more efficient + livable city (but higher housing cost)

GENTRIFICATION

• Definition: wealthier residents move into poorer neighborhoods

• Investment near CBD → rising property values

• Infrastructure improvement → attracts higher-income residents

• Rent increases → displacement of low-income residents

• New businesses replace old local shops

• Result: neighborhood improves economically but increases inequality