Area Code Family Trees
Since 1947, the original 98 area codes have spawned 276 descendants through splits and overlays. Explore the family trees to see how area codes relate to each other.
Largest Family Trees
Area Code 213
CA • 21 descendants
Area Code 415
CA • 14 descendants
Area Code 305
FL • 10 descendants
Area Code 201
NJ • 9 descendants
Area Code 312
IL • 8 descendants
Area Code 212
NY • 7 descendants
Area Code 617
MA • 7 descendants
Area Code 713
TX • 7 descendants
Area Code 205
AL • 6 descendants
Area Code 512
TX • 6 descendants
Interactive Family Tree Visualization
Scroll to zoom • Drag to pan • Click a node to view its area code page
Quick view — select a tree:
Key Findings
- The deepest family tree reaches 4 levels — area codes have been split up to 4 times from their original 1947 assignment.
- The largest family trees belong to codes serving major metropolitan areas like Los Angeles (213), New York (212), and Chicago (312).
- Since 2000, most new area codes have been overlays rather than splits, preserving existing numbers while adding capacity.
All Original Area Codes
These 98 area codes were assigned in 1947 as part of the original North American Numbering Plan. Click any code to see its full family tree on the area code page.
Understanding Area Code Family Trees
Area code family trees show the genealogy of telephone number planning areas. The original 98 area codes assigned in 1947 have grown to 374 through a process of splits and overlays.
Splits vs Overlays
A split divides an existing area code's territory, assigning part to a new code. An overlay adds a new code over the same territory, requiring 10-digit dialing. Most codes since 2000 are overlays.
How to Read the Trees
Each box represents an area code. Lines show parent-child relationships. The root (original) code is at the top, with descendants branching below. Click any code to see its full details and local calling area.