Global population data is in crisis – here’s why that matters

Every day, decisions that affect our lives depend on knowing how many people live where. For example, how many vaccines are needed in a community, where polling stations should be placed for elections or who might be in danger as a hurricane approaches. The answers rely on population data.

But counting people is getting harder.

For centuries, census and household surveys have been the backbone of population knowledge. But we’ve just returned from the UN’s statistical commission meetings in New York, where experts reported that something alarming is happening to population data systems globally.

Census response rates are declining in many countries, resulting in large margins of error. The 2020 US census undercounted America’s Latino population by more than three times the rate of the 2010 census. In Paraguay, the latest census revealed a population one-fifth smaller than previously thought.

South Africa’s 2022 census post-enumeration survey revealed a likely undercount of more than 30%. According to the UN Economic Commission for Africa, undercounts and census delays due to COVID-19, conflict or financial limitations have resulted in an estimated one in three Africans not being counted in the 2020 census round.

When people vanish from data, they vanish from policy. When certain groups are systematically undercounted – often minorities, rural communities or poorer people – they become invisible to policymakers. This translates directly into political underrepresentation and inadequate resource allocation.

As the Brookings Institution, a US research organisation, has highlighted, undercounts have “cost communities of colour political representation over the next decade”.

This is happening because several factors have converged. Trust in government institutions is eroding worldwide, with the Organisation for Economic Co-operation and Development (OECD) reporting that by late 2023, 44% of people across member countries had low or no trust in their national governments. Research shows a clear trend of declining trust specifically in representative institutions like parliaments and governments. This makes people less likely to respond to government-issued census requests.

The COVID-19 pandemic created logistical nightmares for census takers. Many countries had to postpone their censuses. Budget cuts to statistical offices reduced capacity, while countries struggled with recruiting field staff.

International funding for population data is also disappearing. The US-funded Demographic and Health Surveys program, which provided vital survey data across 90 countries for four decades, was terminated in February 2025. Unicef’s Multi-Indicator Cluster program, which carries out household surveys, faces an uncertain future amid shrinking global aid budgets. US government cuts to support for UN agencies and development banks undertaking census support will likely have further impacts.

This is incredibly worrying to us as geography academics, because gathering accurate population data is fundamentally about making everyone visible. As population scientists Sabrina Juran and Arona Pistiner wrote, this information allows governments to plan for the future of a country and its people.

The US census directly impacts the allocation of more than US$1.5 trillion (£1.2 trillion) in public resources each year. How can governments distribute healthcare funding without knowing who lives where? How can disaster response be effective if vulnerable populations are invisible in official population counts?

Solutions that count

Countries are adapting. The COVID-19 pandemic accelerated the transition to alternative census methodologies. Many countries turned to online questionnaires, telephone interviews and administrative data sources to reduce face-to-face interactions.

The UN Economic Commission for Africa recommends that countries move from using paper forms for census data collection and embrace new digital technologies that can be cheaper and more reliable. Turkey’s switch in 2011 reduced census costs from US$48.3 million to US$13.9 million while improving data quality and timeliness, and nearly 80% of countries used tablets or smartphones for data collection in the 2020 round of censuses.

At WorldPop, our research group at the University of Southampton, we’re also helping governments to develop solutions using new technologies. Buildings mapped from satellite imagery using AI, together with counts of populations from small areas, can help create detailed population estimates to support census implementation or provide estimates for undersurveyed areas.

As we face growing challenges, from climate change to economic inequality, having accurate, reliable and robust population data isn’t a luxury. It’s essential for a functioning society. National statistical offices, UN agencies, academics, the private sector and donors must urgently focus on how to build cost-effective solutions to provide reliable and robust population data, especially in resource-poor settings where recent cuts will be felt hardest.

When people disappear from the data, they risk disappearing from public policy too. Making everyone count starts with counting everyone.

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Andrew J Tatem works for the University of Southampton, and is Director of WorldPop. His research on mapping populations has been funded by donors such as the Gates Foundation, Wellcome Trust, GAVI.

Jessica Espey works for the University of Southampton. Her research on data, statistics and evidence use has previously been funded by the William and Flora Hewlett Foundation, Gates Foundation and others.