The savings gap and the Harrod–Domar model, primary product dependency, the foreign currency gap, debt, capital flight, population growth, weak institutions, corruption, geography and conflict; why the obstacles reinforce each other.
The World Bank’s June 2025 update raised the international poverty line to $3.00 a day in 2021 prices, from $2.15, and counted 838 million people, 10.5% of the world, below it in 2022, falling to about 9.9% by 2025. The fall in global poverty since 1990 is one of the great facts of economic history, but it has slowed: most of it came from China and India, where India’s rate fell to 5.4% in 2024, 171 million people above the line in a decade. What remains is concentrated in sub-Saharan Africa and in countries affected by conflict, and nearly three quarters of it is rural. Nigeria has the largest number of extremely poor people of any country; the Democratic Republic of Congo, with vast mineral wealth, has seen its rate barely move.
Why do some countries grow out of poverty and others not? What stands in the way?
Source: World Bank, June 2025 global poverty update and Poverty and Inequality Update, autumn 2025.
Economic obstacles. A savings gap: poor households cannot save, so there is little to invest; the Harrod–Domar model says growth = savings ratio ÷ capital–output ratio, so low saving means slow growth, and the poverty cycle closes. A foreign currency gap: export earnings too small to pay for the capital goods, fuel and food that must be imported. Primary product dependency: exports of one or two commodities whose prices swing wildly and, over the long run, tend to fall relative to manufactured goods (the Prebisch–Singer hypothesis). Debt: interest payments that crowd out health and education, often in dollars that a falling currency makes dearer. Capital flight: wealth moved abroad. Demographic factors: fast population growth that dilutes capital per worker and a dependency ratio that absorbs income. Lack of access to credit and banking, poor infrastructure, low human capital in education and health.
Non-economic obstacles. Weak property rights and institutions, so investment is unsafe; corruption; poor governance; civil war and conflict; geography: landlocked countries, tropical disease, poor soils; and the resource curse, in which oil or minerals bring an overvalued currency, rent-seeking and conflict rather than development.
The obstacles interact: conflict destroys infrastructure, which deters investment, which keeps saving low, which keeps the state too poor to provide education. That is why the countries left in extreme poverty are those with several at once.
In June 2025 the World Bank raised the extreme poverty line from $2.15 to $3 a day. Overnight, 125 million more people were counted as extremely poor.
Nobody got poorer. The new line reflects 2021 prices and what the poorest countries themselves count as poverty. On it, 838 million people, 10.5% of humanity, lived in extreme poverty in 2022.
Where do most of them live?
China and India cut extreme poverty by hundreds of millions; India alone lifted 171 million above the line in a decade. The remaining poverty is concentrated where the obstacles in this lesson pile up: low saving, dependence on a few commodities, debt, weak institutions, conflict and fast population growth.
The savings gap. Harrod–Domar: growth = saving ÷ capital–output ratio. A country saving 12% of GDP with k = 4 grows at 3%. Subtract population growth of 2% and income per head rises 1% a year: seventy years to double. Poor households cannot save, so investment is low, so income stays low, so households cannot save: the poverty cycle.
Check: A country saves and invests 12% of GDP and needs £4 of capital for each £1 of extra annual output. According to the Harrod–Domar model its growth rate is:
g = s ÷ k = 12 ÷ 4 = 3%. With population growing at 2%, income per head rises only 1% a year.
Filling the gap. To reach B and grow at 6% the country must invest 24% of GDP; it saves 12%. The savings gap of 12% can be filled by foreign direct investment, aid or borrowing, each with a price: profits leave, donors attach conditions, debt must be serviced in dollars. Or saving can be raised at home through banking, pensions and tax, the route East Asia took.
Check: To grow at 6% with a capital–output ratio of 4, the country must invest 24% of GDP. It saves 12%. The gap of 12% of GDP can be filled by:
The gap is real resources, not cash; only saving from somewhere, at home or abroad, can fill it. Each source has costs: debt service, profit repatriation, conditions.
Saving is not enough. The capital–output ratio measures how much capital each unit of output needs, and bad institutions raise it: roads that wash away, factories without power, projects chosen for bribes. At C the same 24% of GDP yields 4%, not 6%. This is why corruption, property rights and governance appear in every development answer: they decide how much growth each pound of investment buys.
Teacher tip: The DRC is the standing example of saving that does not become growth: mineral exports worth billions, a capital–output ratio inflated by conflict and corruption, and a poverty rate that has not moved. Harrod–Domar gives students a way to say that precisely.
Check: A country saves 24% of GDP but poor infrastructure, corruption and weak institutions mean each £6 of investment yields only £1 of extra output. Its growth is:
g = 24 ÷ 6 = 4%. The capital–output ratio captures how well investment is used; raising k from 4 to 6 costs a third of the growth.
The foreign currency side. Exports of one or two primary products mean earnings that double and halve with world prices, as cocoa and copper did in 2024–26. A collapse cuts the budget, the currency and the ability to import machinery: the foreign currency gap. Debt in dollars grows in local terms when the currency falls; interest crowds out schools and clinics. Capital flight removes the saving that was there.
Check: A country earning 70% of its export revenue from copper faces which obstacle?
Commodity prices swing far more than manufactured goods prices; a price collapse cuts investment and government spending at once. Prebisch and Singer argued the long-run trend is also against commodities.
The non-economic obstacles. Conflict raises k, cuts s and empties the treasury in one move. Weak property rights make investment unsafe, so capital stays abroad. Geography matters: landlocked countries pay more to trade; tropical disease cuts productivity. Population growth of 3% means saving must rise just to stand still per head. The countries still in extreme poverty face several of these at once.
Check: Which non-economic obstacle most directly explains why extreme poverty is now concentrated in fragile and conflict-affected states?
Conflict reverses development on every front at once and makes every economic obstacle worse.
B is marked at 9%, off the line. With k = 4, 24% saving gives 24 ÷ 4 = 6%. Growth is proportional to saving at a given k; it does not triple when saving doubles.
Evaluate the view that a lack of savings is the main obstacle to growth and development in low-income countries.
The Harrod–Domar model holds that an economy’s growth rate equals its savings ratio divided by its capital–output ratio. A country saving 12% of GDP with a capital–output ratio of 4 grows at 3% a year, and with population growing at 2%, income per head rises by 1%: too slowly to escape poverty within a lifetime. Because poor households consume all they earn, saving stays low, investment stays low and income stays low, which is the poverty cycle. The savings gap between what a country saves and what it would need to invest to grow fast is therefore a central obstacle, and the countries that escaped poverty in the last fifty years, Korea, China, Vietnam, did so with saving and investment rates of 30 to 40% of GDP.
The gap can be filled from abroad. Foreign direct investment, aid and borrowing all substitute foreign saving for domestic, but each has a cost: profits are repatriated, aid comes with conditions and can be misused, and debt must be serviced in foreign currency that a falling exchange rate makes dearer. Developing a domestic financial system that mobilises small savings is slower but more durable.
**However,** saving is necessary, not sufficient. The same model shows that the capital–output ratio matters as much: if corruption, poor infrastructure and weak property rights mean each unit of output needs six units of capital rather than four, 24% saving yields 4% growth rather than 6%. The Democratic Republic of Congo earns billions from minerals and remains among the poorest countries on earth, which no savings gap explains. Primary product dependency makes export earnings and tax revenue swing with world prices; a foreign currency gap stops investment goods being imported whatever the saving rate; debt service crowds out health and education; conflict destroys capital faster than it can be saved; population growth of 3% means saving must rise just to hold income per head. Extreme poverty, now 838 million people on the World Bank’s $3 line, is concentrated in fragile and conflict-affected states, where the binding constraint is the state itself rather than the saving rate.
On balance a lack of savings is one obstacle among several that reinforce each other, and rarely the decisive one. The evidence points to institutions, governance, property rights, peace and a capable state, as the obstacle behind the obstacles: where they are present, saving rises and foreign capital arrives; where they are absent, saving leaves as capital flight and investment yields little. Saving matters, but mainly where the conditions that make it productive already exist.
Poverty figures: World Bank, June 2025 global poverty update (international poverty line raised to $3.00 a day at 2021 purchasing power parity; 838 million people, 10.5%, in 2022; projected 9.9% in 2025) and Poverty and Inequality Update, autumn 2025. The Harrod–Domar lines on the diagram are illustrative. Diagrams drawn with Rough.js and perfect-freehand, both MIT licensed.