More than 1,000 people died during this year’s holy rituals in Mecca, putting new pressure on Saudi Arabia to tackle a growing number of challenges.
In 2008, Saudi authorities began a three-decade, $227 billion project to expand the religious sites. The government is also using live crowd-analytics software to prevent stampedes. Yet with the number of pilgrims soaring from 100,000 in 1920 to a predicted 5 million in 2016, overcrowding is nearly impossible to avoid.
The Saudi health ministry has tried to raise awareness about diseases like cholera, dengue fever and meningitis and made certain vaccinations mandatory for pilgrims. Preventing an outbreak of the deadly MERS virus is also a key health concern.
After attacks on Sunni and Shi’ite mosques in Saudi Arabia by the jihadist group ISIS, authorities deployed some 100,000 security personnel to guard hajj sites. But heightened sectarian tensions across the region mean that risk is unlikely to subside anytime soon.
This appears in the October 12, 2015 issue of TIME.