If you extrapolate developmental indicators historically (eg. the AHDI [0]), India in the 2010-2020 period is roughly comparable to the US in the 1950-1960 period.

None of this is surprising if you have an background with US economic history. Similar to India today, the US in the 1940-1970 period had an industrialized half (the North, Midwest, and Western US) and less industrialized hinterland (Appalachia, South, Southwest).

A major component of America's development was because of massive industrial projects targeting Appalachia, South, and Southwest America (eg. TVA, Space Grants, NASA Huntsville, Interstate Highways) along with the expansion of the social safety net.

India is seeing a similar transformation via large industrial projects and an expansion of the social safety net via welfare programs/yojanas/"freebies".

This can be seen starkly with Rajasthan (INC run) and Gujarat (BJP run). Both share a similar culture and had similarly laggard developmental statistics in 2000, yet by 2019 both have converged with each other [1], as well as at the developmental work occurring in both Uttar Pradesh (BJP run) and Odisha (non-BJP run).

[0] - https://frdelpino.es/investigacion/en/category/01_social-sci...

[1] - https://en.m.wikipedia.org/wiki/List_of_Indian_states_and_un...