Impact of Transport Infrastructure Investment on Regional Economic Growth: Evidence from North West Nigeria

The relationship between transport infrastructure investment and regional economic growth has been extensively theorised but remains empirically contested in the Nigerian context due to data limitations and methodological gaps. This study provides empirical analysis of the impact of transport infrastructure investment on regional economic growth in North West Nigeria, covering Sokoto, Kano, Kebbi, Kaduna, Katsina, Zamfara, and Jigawa states. Using panel data from the Nigerian Bureau of Statistics and the Federal Ministry of Works for the period 2014 to 2024, the study employs a fixed-effects panel regression model with transport capital stock proxied by road network quality indices and highway expenditure per capita as independent variables. Gross domestic product per capita at the state level and agricultural output value serve as dependent variables. Findings show a statistically significant positive relationship between transport infrastructure investment and regional economic growth, with a one percent increase in road quality index associated with a 0.38 percent increase in state-level GDP per capita over a two-year lag period. The impact is found to be stronger in agriculturally productive states, confirming the transport-agricultural productivity channel. However, the study also identifies diminishing marginal returns on infrastructure investment in states with higher existing stock, suggesting investment prioritisation in the most underserved corridors. These findings fill an empirical gap in transport economics literature on Nigeria's North West and provide evidence for infrastructure allocation decisions. Keywords: transport infrastructure, economic growth, North West Nigeria, panel data, road investment.