In Quintana Roo the coast was chosen before the city existed.

Start with what is hard to believe on landing. Quintana Roo covers 44,705 square kilometres on the eastern edge of the Yucatán Peninsula; its highest point does not reach 230 metres, and according to the 2020 census 1,857,985 people live in it. More than 130,000 hotel rooms, according to figures cited in the Mexican press, are spread along that coastline. And yet barely half a century ago none of that existed where its largest city now stands.

01 A list of criteria and three residents

In 1967 the Mexican government set aside a two-million-dollar fund, administered by the Bank of Mexico, to study where new recreation zones could be opened. The job passed to a trust, INFRATUR, and accounts of the project say computing tools were used in the analysis, unusual for the time. The factors weighed were concrete: climate, beach quality, hurricane risk, availability of labour and distance to the US market. Acapulco, then the country's great resort, was showing signs of overcrowding, and another was needed.

The result pointed to a long island joined to the mainland by strips of sand and mangrove. Works began on 23 January 1970. At that moment the island had three residents, the caretakers of a coconut plantation; the nearest settlement, Puerto Juárez, had around 117 inhabitants. The island could only be reached by boat, so the first things built were a road from Puerto Juárez and a provisional airstrip.

That is the difference from almost any other coastal destination. Here the list of criteria came before the city: INFRATUR bought more than 12,000 hectares and divided them by use (tourist zone, lagoon system, conservation land and urban area) before there was anyone to house. The first hotels opened in 1974, when a successor fund, FONATUR, took control and organised growth in three phases: the hotel zone, the city for those who would work in it, and the international airport.

02 A strip between two waters

What the planners chose has a very particular shape, and it makes sense as soon as you see it from above: a ribbon of land with the open Caribbean on one side and a lagoon, Nichupté, on the other. That is why the main road of the hotel zone runs, literally, between two waters: turquoise surf on the left and a flat, darker surface on the right, almost without movement. One avenue, two landscapes of water that look nothing alike.

The lagoon was not left as it was either. The works included large-scale dredging that removed mangrove and connected the lagoon system to the sea. The consequence today is that this inner edge is the most fragile part of the whole: pollution and deterioration have been documented in the lagoon, and the beaches on the sea side need periodic sand replenishment. A designed strip demands continuous upkeep.

03 The reef a few hundred metres out

One criterion on the list could not be manufactured by a planner: the beach. Along much of Quintana Roo's shoreline, the sea that reaches the sand has already passed over a reef. Off Puerto Morelos, south of Cancún, the reef runs a few hundred metres from the coast (sources give between 400 and 500) and waves break on it; what lies behind is a calm reef lagoon. It is the Mexican part of a system that continues south as far as Honduras, and the Puerto Morelos stretch has been a national park since 1998.

This is what the 1967 list took for granted without being able to build it: a clear-water shoreline with a natural breakwater a short way out. What was built on top, hotels, avenues and airport, depends on that living band of coral running under the water. Corals such as elkhorn (Acropora palmata), which forms broad, flat branches, live there, and shoals of small fish move among them.

04 What was left off the list

If the state were read only through Cancún, it would look like a piece of engineering. But head south and the other layer appears. In the municipality of Tulum, the Sian Ka'an Biosphere Reserve covers about 5,280 square kilometres (an area equal to almost 12% of the state) of land, wetland and a stretch of reef. It was declared a biosphere reserve in 1986 and inscribed by UNESCO as a World Heritage Site in 1987.

The contrast is the key to reading the place. There, no trust divided the land by use: what exists is continuous low forest, lagoons, and the remains of some 23 known Maya archaeological sites inside the reserve, Muyil among them. The part of the coast that nobody chose for anything else is still, largely, what it was; and that is why the state shows both how the shoreline was and how it was decided to transform it.

05 What it means on the ground

A city born from a plan has a different rhythm from one that accumulates. The figures show it: Cancún had 167,730 inhabitants in 1990, 397,191 in 2000 and 888,797 in 2020. Those 888,797 are almost half (48%) of Quintana Roo's entire population, concentrated in a single municipality. Growth outran the plan: the workers the project foresaw were joined by thousands more who came from other regions of Mexico, and the city conceived for them did not always suffice.

For someone spending a few days here, the consequence is an uncommon feeling: a place where almost everything has a design reason. The avenue runs between sea and lagoon because the strip was that narrow; hotels cluster where the plan put them; the airport is where the third phase placed it. And a few hours by road to the south is the counterpoint: a shoreline that follows its own logic, that of mangrove, lagoon and reef.

That is the difference that explains Quintana Roo. It is not a destination that formed gradually over time, but one whose geography was read first with a table of criteria and then built. Remove the name and it is still recognisable: a coast that answers to a decision of 1967, with a strip between two waters and, behind it, a reef that was already there.