In recent times, rising insecurity and crimes are some of the major problems confronting Nigeria. However, crimes vary significantly across the States in the country. This study, therefore, investigated the effects of State's economic gaps on crimes employing panel instrumental variables technique for 21 States in Nigeria and Federal Capital Territory (FCT) between 2016 and 2017. The results showed that States' income per capita is not crime reducing but States' income per capita gaps. A 10% reduction in States' income per capita gaps reduced all crimes and crimes against people by 1.8% and 3.0%, respectively. Also, 10% increase in the population density increased crimes against the authority by 7.0%. Reducing State's economic gaps and population reducing policy would be effective approaches at minimising crimes in Nigeria.