With better incomes come superior socio-economic characteristics. Life expectancy in the south is more than elsewhere, the literacy rate too is noticeably better, and the southern woman gives birth to one child less than her northern counterpart. Indeed, fertility has fallen below the replacement rate of two births per woman in at least two states, so in due course the southern population could start shrinking while that north of the Godavari (a better marker of the divide than the usual reference point, the Narmada) continues to grow.
These imbalances create others, like tax revenue raised by the state. Jharkhand, which has the same population as Kerala, has less than half its own tax revenue. Ditto with Madhya Pradesh compared to Tamil Nadu. This imbalance in fiscal firepower is partly corrected through central transfers: The southern five contribute about a quarter of the revenue from the central goods and services tax (GST), for instance, but their share of total central transfers to states is less than a sixth. This is as it should be, for without a disproportionate transfer of central resources, the poorer states will fall further behind. The southern states have not complained. But even with skewed transfers, the gap remains a chasm.