How Boundary Agreements Reduce Wars Between Neighboring States

Why This Question Matters

Can signing agreements that clearly mark territorial borders make neighbors less likely to fight? Andrew P. Owsiak tackles this long-standing claim about the pacifying power of border settlement—a topic with direct implications for diplomacy, conflict prevention, and theories of interstate war.

New Data on Boundary Agreements

Owsiak assembles a new, historically comprehensive dataset of international boundary agreements covering 1816–2001. This database records when neighboring states formally settle their borders and provides the foundation for a systematic test of whether those settlements change the trajectory of bilateral relations.

How the Claim Is Tested

The study conducts the first thorough, long-range empirical test of the link between settled borders and interstate conflict. Using statistical models of militarized interstate disputes (MIDs) and wars between neighbors, the analysis controls for important alternative explanations—most notably joint democracy, which the author shows is positively associated with settled borders. Robustness checks examine the relationship across multiple time periods to assess consistency.

Key Findings

• Neighbors that settle their borders through formal agreements are less likely to experience militarized interstate disputes or full-scale interstate wars with one another.
• The pacifying association of boundary settlement remains after controlling for joint democracy and other covariates; joint democracy itself makes border settlement more likely but does not fully explain the peace effect.
• The reduction in conflict linked to settled borders persists across several historical periods, suggesting the effect is not confined to a single era.

What This Means for Scholarship and Policy

Owsiak’s results suggest that diplomatic efforts to formalize territorial boundaries can have durable peace dividends independent of regime type. For scholars, the study highlights border agreements as a distinct institutional mechanism shaping interstate peace; for practitioners, it underscores the potential value of negotiated boundary settlement in conflict-prone regions.