When people refer to the United States as a whole, they often use the words conterminous and contiguous interchangeably. However, these two terms do not mean exactly the same thing. Understanding the difference between the conterminous United States and the contiguous United States helps clarify discussions about geography, travel, government, and mapping. While both terms describe the main body of the country, each has its own specific definition that reflects how the United States is organized and connected geographically.
Meaning of the Contiguous United States
The phrase contiguous United States refers to the 48 adjoining states that are connected to each other geographically, along with the District of Columbia. This area forms one large continuous landmass without any physical separation by ocean or foreign territory. The contiguous states stretch from the Atlantic Ocean in the east to the Pacific Ocean in the west, and from the Canadian border in the north to the Mexican border in the south.
When people mention the lower 48, they are referring to these contiguous states. This term excludes Alaska and Hawaii because those two states are not physically connected to the rest of the country. Alaska is separated by Canada, while Hawaii lies in the Pacific Ocean, about 2,400 miles away from the mainland.
Meaning of the Conterminous United States
The word conterminous is closely related to contiguous but carries a slightly different nuance. The conterminous United States refers to the same 48 states and the District of Columbia that share common boundaries and form one continuous area. However, conterminous technically focuses on having common or shared boundaries rather than simply being connected physically.
In practice, conterminous is often used as a synonym for contiguous. However, some geographers and government agencies prefer conterminous because it more accurately describes areas that share a border or boundary. It emphasizes the administrative or territorial aspect of being connected, rather than just the physical geography.
Key Differences Between Conterminous and Contiguous
Although the two words are frequently used interchangeably, there are subtle distinctions between them. Understanding these differences can help avoid confusion in academic writing, cartography, or discussions involving U.S. geography.
1. Geographical Emphasis
Contiguous focuses on the physical connection between the states. It means the states are touching each other and form a continuous block of territory. Conterminous, on the other hand, focuses on the idea of sharing a common boundary or being within the same limits. This term is more conceptual and relates to the legal or administrative unity of the region.
2. Common Usage
In everyday English, contiguous United States is the more popular term, especially in travel, weather reports, and media. For example, when the National Weather Service issues a forecast for the contiguous United States, it means it applies to the 48 connected states. Conterminous is used less frequently and is more common in academic, geographic, or legal contexts.
3. Linguistic Roots
The word contiguous comes from the Latin contiguus, meaning touching or bordering. It emphasizes physical closeness. Conterminous derives from the Latin conterminus, meaning having a common boundary. It points to the shared limits or edges of regions. Although similar in origin, their connotations diverge slightly.
Examples in Geographic Context
To make the distinction clearer, consider a few examples
- The 48 contiguous states share borders with each other, forming one massive landmass. Driving from California to New York is possible without crossing into another country.
- Alaska, while part of the United States, is not contiguous because it is separated from the lower 48 by Canada.
- Hawaii is neither contiguous nor conterminous with the mainland since it is an island chain in the Pacific Ocean.
- Both Alaska and Hawaii are part of the conterminous national boundaries of the United States as a political entity, but not of the contiguous land area.
Relation to the Continental United States
Another term often mentioned alongside contiguous and conterminous is continental United States. This phrase refers to all states on the North American continent, including Alaska but excluding Hawaii and other island territories. The continental U.S. includes the 48 contiguous states plus Alaska, since both are located on the North American continent. This term is especially useful in discussions about continental geography, wildlife, and land features.
In summary, the main differences among these related terms are
- Contiguous United StatesThe 48 connected states plus the District of Columbia.
- Conterminous United StatesUsually the same as contiguous, emphasizing shared boundaries.
- Continental United StatesThe 48 contiguous states plus Alaska, excluding Hawaii and territories.
Why These Terms Matter
Although these terms may seem interchangeable, they are important for legal, geographic, and governmental accuracy. For example, federal agencies use these distinctions when defining data sets, conducting censuses, or determining eligibility for programs based on location. A travel advisory for the contiguous United States would not apply to Hawaii or Alaska, but one for the continental United States would include Alaska.
Additionally, weather forecasting and environmental studies often focus on the contiguous states because they share similar climate zones, land connections, and ecosystems. Including Alaska or Hawaii would require different analyses due to their distinct geographic and climatic conditions.
Common Misunderstandings
Many people mistakenly use continental when they mean contiguous. For example, someone might refer to continental flights when they actually mean flights within the connected 48 states. Technically, a flight from California to Alaska is continental but not contiguous. Similarly, some assume that conterminous and contiguous mean the same thing without understanding their subtle difference in emphasis.
In legal or policy documents, precision matters. For instance, a report on conterminous regions might refer to states that share a boundary within the U.S., whereas one on contiguous areas focuses on the continuous geographical layout of the land.
Historical Development of the Terms
Both contiguous and conterminous entered English during the early modern period, drawing from Latin roots used in land surveying and territorial law. As the United States expanded westward, these terms became useful for describing connected and disconnected territories. Before Alaska and Hawaii achieved statehood in 1959, the term contiguous United States referred to the states connected by land, while the continental United States included all North American holdings.
After statehood, Alaska’s inclusion as part of the continent but not the contiguous area created new distinctions in geography, travel, and military planning. For instance, during World War II, military communications often referred to the contiguous states when discussing logistics within the main landmass.
Applications in Modern Use
Today, these terms appear in various contexts beyond geography. In education, textbooks use them to teach U.S. geography and physical boundaries. In logistics and business, companies often specify shipping policies that apply only to the contiguous United States because shipping to Alaska, Hawaii, or island territories involves higher costs.
Similarly, the U.S. Census Bureau, National Weather Service, and Department of Defense all use these distinctions for clarity. For instance, when reporting population data or weather patterns, agencies may limit the scope to the contiguous United States for consistency and comparability.
Examples in Everyday Life
The difference between the contiguous and conterminous United States can appear in various aspects of daily communication. For instance
- Online retailers often advertise free shipping within the contiguous U.S., meaning Alaska and Hawaii are excluded.
- National parks and road trip guides often use contiguous United States when describing travel routes connecting all 48 states.
- Government reports might use conterminous United States in official language to describe shared administrative boundaries.
The terms conterminous United States and contiguous United States both refer to the 48 connected states and the District of Columbia, but each emphasizes a different aspect of connection. Contiguous highlights the physical continuity of the land, while conterminous focuses on shared boundaries within the same limits. Although their meanings overlap in common usage, their subtle distinctions are valuable in geography, law, and government. Understanding these differences not only improves accuracy in communication but also deepens appreciation for the complexity of how the United States is organized geographically and politically. Whether discussing travel, policy, or natural geography, knowing when to use each term ensures clarity and precision in describing one of the world’s most expansive nations.