Executive Summary

Highway numbering is often assumed to be a neutral technical exercise, but in practice it is a deeply political process. Split numbers—instances where a single route number is assigned to two or more discontinuous or parallel branches—arise from political bargaining, local pressures, funding incentives, and institutional inertia. The presence of primary, secondary, and split designations affects not only wayfinding but economic development patterns, jurisdictional authority, and public perception of infrastructure priority.

This white paper analyzes the political dynamics behind split numbering systems and the governance, economic, and social consequences they produce. It also provides policy recommendations for modern transportation agencies seeking to balance administrative coherence with local political realities.

1. Introduction

Highway numbering systems were originally created to reduce confusion. Over time, however, political and bureaucratic forces have overridden the pure logic of cartography. In the United States—though similar dynamics occur worldwide—split highway numbers emerged largely from congressional or state-level compromises, county lobbying, and the piecemeal evolution of road networks.

Primary, secondary, and split road labels now serve as political symbols of prestige, gateways to funding formulas, and indicators of regional influence. Understanding these causes and consequences is crucial for transportation planners, policymakers, and scholars of infrastructure politics.

2. Historical Background: Why Road Numbers Became Political

2.1 Early Numbering as Technical Rationalization

Originally, numbering schemes in the U.S., Canada, and Europe were built around simple grids or radial hierarchies. Roads were assigned numbers based on:

Direction (odd for north–south, even for east–west) Position (lower numbers in the east/north, higher in west/south) Importance (one- or two-digit numbers for major routes)

But this tidy system quickly collided with real-world political forces.

2.2 The Federal–State–Local Power Struggle

Over time, multiple layers of government developed vested interests in specific route numbers. These interests included:

Federal branding: U.S. Highways and later Interstates conferred national prestige. State pride and identity: Governors and legislatures often resisted renumbering that could make a region appear less important. Local economic interests: Towns feared losing traffic if their route number changed or was downgraded.

As a result, numbering choices increasingly reflected negotiated political outcomes.

3. The Political Causes of Split Highway Numbers

Split highways generally arise from one or more of the following political pressures.

3.1 Local Resistance to Downgrading

When a route is relocated or improved, transportation agencies often want to retire the old alignment. Local governments fight back because:

The original route may still be a commercial corridor, and losing a major number is seen as economic harm. Residents perceive a downgrade as symbolic abandonment. Legislators resist angering constituents.

To placate these interests, agencies “split” the number so that the old alignment keeps its designation (e.g., US-25E and US-25W).

3.2 Regional Rivalries and Political Balancing

Split numbers often reflect an unwillingness to choose “winners” and “losers” between competing corridors. Legislators may insist that:

Both routes receive equal recognition Funding formulas remain accessible on both sides Neither region appears disadvantaged

This results in politically manufactured dual branches of the same number.

3.3 Funding Eligibility Tied to Route Classification

Primary route numbers frequently unlock higher tiers of state or federal funding. Keeping an old or parallel route under the same number allows local governments to argue for:

Maintenance budgets Safety improvements Economic development investments

Thus, split numbering becomes a tool for maximizing access to funds.

3.4 Legacy Constraints and Institutional Inertia

Some splits exist because changing them would require:

Rewriting state statutes Modifying MPO (Metropolitan Planning Organization) long-range plans Replacing thousands of signs Re-educating the public

Agencies often accept split numbers as the “least bad” political compromise.

3.5 Political Branding and Identity Narratives

Communities sometimes identify with a route historically tied to the area. When highway modernization reroutes traffic, they lobby to keep “their number” alive. Politicians support these efforts as symbolic gestures of loyalty.

4. Consequences of Split, Primary, and Secondary Road Labels

4.1 Public Confusion and Degraded Wayfinding

Split numbers reduce navigational clarity:

Drivers cannot infer continuity from a number. GPS routing can become inconsistent or counterintuitive. Emergency services face coordination challenges on similarly labeled but non-contiguous roads.

From a human-factors standpoint, split numbering undermines the purpose of classification systems.

4.2 Economic and Developmental Effects

4.2.1 Primary vs. Secondary Designations

Primary routes attract:

Higher traffic volumes State-level investment Business development (retail, logistics, hospitality)

Secondary or spurred routes receive:

Less funding Lower maintenance priority Reduced political attention

The label alone can shape development trajectories for decades.

4.2.2 Split Designations and Local Economies

A split number keeps the appearance of parity between regions, even when traffic flows differ. This can:

Shield declining corridors from complete economic marginalization Encourage investment based on outdated perceptions Create mismatched expectations among local stakeholders

In some cases, split numbering artificially maintains economic competition between adjacent communities.

4.3 Administrative Complexity and Cost

Split numbering increases:

Signage costs Data-management burdens Map and routing inconsistencies Legal ambiguities in state transportation codes

Over time, these administrative costs compound.

4.4 Political Messaging and Territorial Claims

Highway labels communicate priority. A “primary” route signals:

State commitment Federal connection Strategic economic status

Secondary or auxiliary labels (“A,” “B,” spur routes, business loops) implicitly classify communities as less central. These classifications can shape political perceptions and even influence legislative districting arguments.

4.5 Safety Consequences

Confusing numbering can:

Increase driver error rates Cause misrouting of heavy trucks Lead to mistaken detours during closures or disasters

When two branches share a label, emergency communications must expend additional effort to clarify which segment is affected.

5. Case Studies (Generalized and Abstracted)

5.1 An Eastern Split Highway (E/W Branch)

A state faced competing demands from two mountain corridors seeking to remain on a national route. Rather than choose a single alignment for the federal designation, legislators pressured transportation departments to maintain both as U.S. Highways.

Outcome: decades of navigational confusion, different economic outcomes for each branch, and persistent debates about which corridor should be prioritized for improvements.

5.2 A Midwestern Primary Route Reassignment Controversy

A new freeway bypass was constructed to improve freight mobility. Towns along the old route lobbied successfully to retain the original number as a “Business” or “Alternate” route.

Outcome: multiple designations, duplicated numbers, and split funding priorities across the corridor.

5.3 A Southern Corridor with Intensely Political Numbering

Two competing metropolitan areas demanded that a major route pass through their region. Unable to resolve the dispute politically, the state DOT assigned a single number with permanent split branches.

Outcome: long-term inefficiency, unequal traffic distribution, and inter-regional rivalry embedded in the numbering system.

6. Policy Implications

6.1 Governance Implications

Transportation agencies must navigate:

Legislative mandates Local lobbying MPO regional politics Funding formulas tied to classifications

The result is often sub-optimal system design from a purely technical viewpoint.

6.2 Strategic Communication Needs

Because numbers carry political meaning, any renumbering initiative requires:

Public education campaigns Legislative coordination Economic impact mitigation plans

Agencies must treat highway numbering as a political change management process, not a technical adjustment.

6.3 Balancing Clarity with Political Reality

Some states have successfully reduced split numbering by:

Introducing explicit “Business,” “Alternate,” or “Scenic” designations Offering economic transition support to communities losing primary status Replacing route numbers with neutral corridor identifiers

Others have failed due to lack of stakeholder alignment.

7. Recommendations

7.1 For State Transportation Agencies

Prioritize numbering clarity even when pressured by local interests. Use distinct suffixes (Business, Alternate) rather than parallel mainline numbers. Commission economic impact studies to inform renumbering decisions. Develop transparent criteria for primary/secondary designations.

7.2 For Legislatures

Avoid statutory micromanagement of route numbers. Provide transition funding for communities affected by downgrades. Encourage long-term corridor planning to reduce political fragmentation.

7.3 For MPOs and Local Governments

Understand that number retention may provide short-term benefits but long-term confusion. Align regional priorities to avoid creating competing political claims on the same corridor. Use branding strategies independent of state route numbers to maintain local identity.

8. Conclusion

Split highway numbers are a visible manifestation of the deep political dynamics that shape transportation infrastructure. While numbering systems are expected to provide clarity, they often reflect compromises among legislators, local governments, DOTs, and economic stakeholders.

The presence of primary, secondary, and split road labels carries political, economic, administrative, and safety consequences that influence development patterns and public perception for decades.

Policymakers and transportation planners who understand the political origins of these numbering decisions will be better equipped to reform them—or to design future systems that avoid repeating the same errors. Ultimately, numbering should serve the traveling public, not just political convenience.