Definition
The 48 adjoining states of the United States plus the District of Columbia, all sharing common borders within a single continuous land area. Alaska and Hawaii are excluded because they do not share a border with the other states.
Plain English
The 48 states that all touch each other on the mainland, plus Washington D.C. It does not include Alaska or Hawaii.
Context Anchor
Seen in FAA regulations, weather products, chart coverage, and operating rules that apply only to the main connected U.S. states.
Derivation
From Latin 'con-' (together) and 'terminus' (boundary or end). Literally 'sharing a common boundary.' This is why Alaska and Hawaii are excluded — they do not share a land border with the rest of the states.
Why Pilots Care
Many FAA rules, airspace procedures, and weather products apply only inside the conterminous United States and differ for Alaska and Hawaii.
Intuition Check
Do not read “United States” here as every place under U.S. authority. In this term, it means the connected mainland states, not Alaska, Hawaii, or U.S. territories.
Example Sentence 1
The new airspace rule applies throughout the conterminous United States but not in Alaska.
Example Sentence 2
Certain ADS-B requirements apply throughout the conterminous United States but have different deadlines in Alaska.