Last week I mentioned the Economic Survey 2021-22 published by India’s Ministry of Finance. As usual, most of this annual report is an overview of fiscal, monetary, and trade developments, along with discussions of sectors like agriculture, industry/infrastructure and services, as well as employment, social infrastructure, and sustainable development. The last chapter of this year’s report focuses on “Tracking Development through Satellite Images & Cartography.”

One prominent example is called “night lights,” which is just a satellite picture of light emissions at night. The left-hand photo shows India in 2012; the right-hand photo is India nine years later in 2021. The spread of electric lighting in India is clear.

The use of night lights data as a way of estimating economic development has been a research topic for a few years now. For economists, one advantage of night lights data is that it isn’t produced by the national government–unlike, say statistics on gross domestic product. For a discussion of using night lights data to estimate GDP, see Noam Angrist, Pinelopi Koujianou Goldberg, and Dean Jolliffe, “Why Is Growth in Developing Countries So Hard to Measure?” in the Summer 2021 issue of the Journal of Economic Perspectives. (Full disclosure: I’m the Managing Editor of the JEP, which is freely available online to all courtesy of the American Economic Association.)

These authors also point out that satellite imagery is not limited to luminosity: for example, it’s also possible to look at plant cover and even to identify different kinds of plants. For example, here’s a photo of agricultural activity near a certain reservoir after the water infrastructure was improved. Again, if the choice is between trusting a government report on the benefits of the improved infrastructure or trusting a satellite image that can be readily double-checked, the satellite image has some obvious benefits.

It’s also possible to use satellite images to look at industrial development or urban patterns. Here’s a photo of a “wasteland” area before and after it is converted to industrial uses.

In urban areas of some developing countries, attempting to count buildings and land-use through a ground-level army of census-takers (say, for purposes of calculating property taxes) may be a difficult and costly task. Satellite photos offer an overview.

One can also use satellite photos for environmental purposes: for example, to get a clear view of the size of the Amazon rain forest or the extent of cultivated land. Here’s an example from India, looking at the annual cycle of water storage at a certain reservoir.

Finally, there can be cases where good old maps, unassisted by satellite images, can tell a story. Here’s a comparison of the extent of India’s national highway system, as the network doubled its road-miles from 10 years ago up to the present.

It’s easy enough to find lengthy and legitimate lists of concerns about India’s economic growth. But these kinds of images make clear that India’s growth is indeed very real. Those who want to to read more about India’s economy from a broader perspective than this year’s Annual Survey might start with the three-paper “Symposium on the Economics of India” in the Winter 2020 issue of the Journal of Economic Perspectives:

— “Dynamism with Incommensurate Development: The Distinctive Indian Model,” by Rohit Lamba and Arvind Subramanian

— “Why Does the Indian State Both Fail and Succeed?” by Devesh Kapur

— “The Great Indian Demonetization,” by Amartya Lahiri