How Bihar is using night-time light to gauge its economic growth

According to a night-time light study published this March, while Patna, Vaishali, Muzaffarpur, Gaya and Begusarai at top five districts in terms of faster economic growth, Arwal, Jehanabad, Jamui, Banka and Madhubani are top five “emerging districts”. Called ‘The Night Light density and industrial contribution to Bihar’s economic growth’, the study was conducted by Bihar’s industry department in collaboration with the Asian Development Research Institute (ADRI) and submitted recently to the state government.

Arwal, Jehanabad, Jamui, and Banka are all districts that were once affected by Maoist violence.

The study looked at satellite images from 2017 to 2023 to assess high-density areas of light during nights across Bihar and correlated it with its economic growth. It found that the state has recorded 351 percent increase in NTL “with urban centres like Patna, Muzaffarpur, Vaishali, Gaya, and Begusarai showing the highest growth”.

“Specific blocks such as Bihta, Sonepur, Begusarai, Mushahari, and Bidupur witnessed the most significant changes in luminosity,” the 60-page study said.

Over the last few years, economists have realised the importance of studying night-lights, using it to gauge economic growth, poverty and inequality, among other things.

“Light is an indicator of economic growth because all industries and businesses need electricity. Bihar’s industrial future lies in its emerging corridors. Light index can be studied further till block levels to map economic development”, Arpan Sharma, a Geographic Information System (GIS) expert at ADRI, explained.

According to the study, the state capital of Patna, which had night-time illumination in 409 square km area in 2017, stood at 485 sq.km in 2023. Muzaffarpur’s NTL went up from 88 sq.km to 309 sq.km and Vaishali’s from 50 sq.km to 287 sq.km during the period, as shown by satellite images.

Among fast emerging districts, NTL in Arwal went up from 4 sq.km to 50 sq.km, while Jehanabad went from 14 sq.km to 152 sq.km.

The study then correlated its findings with other data such as employment, and found that “construction, retail, agriculture, and animal husbandry are the dominant sectors in districts with the highest night light luminosity”.

“These sectors, largely operating within the unorganised or small and medium enterprise (SME) segments, play a pivotal role in Bihar’s economy. The Periodic Labour Survey Data highlights the significance of commercial crop production, animal husbandry, and transportation as supporting activities contributing to economic vibrancy,” the study said.

Electricity has always been a great marker of economic development, Bihar Industry minister Nitish Mishra told The Indian Express.

“When we electrified the entire state, we wanted to understand what electrification meant and what are its takeaways for us. We had just 17,739 industrial consumers in 2012 and it went up to 1,86,254 in 2025. Consumers using electricity for agriculture purposes also increased from 84,023 in 2012 to 7,23,000 in 2025,” he said, adding that there were “many positive takeaways from NTL study, right from giving us growth and employment markers to making some good suggestions”.

ADRI member secretary and economist Asmita Gupta, who headed the study, said the study showed “growth in food processing, and private healthcare services”.

“Patna has a significant concentration of general manufacturing and textile sectors. NTL also suggested that plastic, rubber, leather, and IT have a limited presence across the regions with lower numbers, especially in smaller districts like Begusarai and Vaishali,” she said.

The biggest takeaway, she said, was that 51 percent of employment in Patna was through start-ups in IT/ITES, e-commerce, and healthcare sectors.

“The number of startups units are highly concentrated in Muzaffarpur, Darbhanga and Bhagalpur are secondary hubs. Gaya, Arwal and Banka have relatively fewer units,” she said.

She added: “Something to take heart from the study findings is once Maoist-infested districts of Banka, Jamui, Arwal and Jehanabad being among top five emerging districts (Madhubani being the fifth district) in terms of economic growth”.