No car may honk nor lorry rumble near secondary schools on the two days in June when students are taking their university entrance exams, known as gaokao. Teenagers have been cramming for years for these tests, which they believe (with justification) will determine their entire future. Yet it is at an earlier stage of education that an individual’s life chances in China are usually mapped out, often in ways that are deeply unfair.

To give more students access to higher education, the government has increased its investment in the sector five-fold since 1997.

The number of universities has nearly doubled. In 1998, 46 percent of secondary-school graduates went on to university. Now 88 percent of them do. About 7 million people — roughly one-third of those aged between 18 and 22 — now gain entry to some form of higher education institution each year.

China’s universities offer more opportunity for social mobility than in many other countries, says James Lee of the Hong Kong University of Science and Technology. But the social backgrounds of those admitted have been changing. Until 1993, more than 40 percent of students were the children of farmers or factory workers. Now universities are crammed with people from wealthy, urban backgrounds. That is partly because a far bigger share of young people are middle-class. But it is also because rural students face bigger hurdles getting into them than they used to.

The problem lies with inequality of access to senior high schools, which take students for the final three years of their secondary education. Students from rural backgrounds who attend such schools perform as well in the university entrance exams as those from urban areas. But most never get there. Less than 10 percent of young people in the countryside are admitted into senior high schools compared with 70 percent of their urban counterparts. The result is that a third of urban youngsters complete tertiary education, compared with only 8 percent of young rural youth.

As in India, schools in the countryside are far weaker academically than urban ones. Local governments invest less in them per student than they do in cities. Urban parents tend to be better educated and thus better able to help children with their studies. Rural pupils often suffer from a “poverty of expectations”, says Jean Wei-Jun Yeung of the National University of Singapore: they are not encouraged to think they can succeed, so they don’t try to.

In China, meritocratic exams have been revered since imperial times, when any man could sit them to enter the civil service. For centuries, they enabled the poor yet talented to rise to high office. The gaokao is similarly intended to be a great leveller. But society has become increasingly divided between those with degrees and those who never even went to senior high. That will mean growing numbers for whom social advancement will remain a distant dream.