The structure of borders in a small world

Area of Science:

• Sociology
• Political Science
• Economics
• Geography
• Network Science

Background:

• Administrative borders are crucial for understanding societal phenomena but may not reflect current human connectivity.
• Modern communication and travel patterns complicate the definition of borders that accurately represent human interaction scales.
• The emergent border structures from multi-scale human interactions remain an open research question.

Purpose of the Study:

• To analyze a multi-scale human mobility network in the United States.
• To compute effective geographic borders inherent to human mobility patterns.
• To develop computational techniques for extracting and quantifying the strength of these borders.

Main Methods:

• Analysis of a massive proxy dataset of human mobility.
• Development and application of two computational techniques for border extraction and strength quantification.
• Comparison of emergent borders with existing administrative boundaries and gravity models.

Main Results:

• Effective geographic borders derived from mobility data only partially overlap with administrative borders.
• Some of the strongest mobility-defined borders are located in unexpected regions.
• Observed mobility structures could not be replicated by traditional gravity models.

Conclusions:

• Human mobility patterns define effective geographic borders that differ from administrative ones.
• The concept of link significance helps elucidate the structure of these emergent borders.
• This novel framework provides a quantitative approach for analyzing spatially embedded interaction networks and their associated phenomena.