Whoever held this spit held the Paraíba, and therefore held the colonial capital upriver at Filipeia de Nossa Senhora das Neves — now João Pessoa. The Portuguese knew it. Cabedelo dates its founding to 4 November 1585, when work began on a fortification at the estuary mouth. Frutuoso Barbosa's first structure was destroyed in 1591; a stone replacement rose from 1592 and was finished in 1597, built during the Iberian Union under Philip I. The Fortaleza de Santa Catarina that resulted is an irregular polygon with two bastions and four vertices, later given pentagonal corner bastions in reworkings from 1618 — the geometry of the age, adapted to a site nobody could afford to lose.

The Dutch took it in December 1634, and only after a long siege. Johan Maurits van Nassau then did what conquerors with money do: he renamed the fortress Margaretha, after his sister, and spent thirty-one thousand florins rebuilding it into something considerably better than what he had captured — a handsome landward bastion, supporting demi-bastions, a tenaille across the approach. The town itself was renamed Margarida. Twenty years later the Dutch capitulated at Recife, and in 1654 Portuguese troops under Colonel Francisco de Figueiroa reoccupied both Santa Catarina and neighbouring Fort Santo Antônio. In 1817, during the Pernambucan Insurrection, the fortress served as a political prison. IPHAN listed it on 24 May 1938, restoration ran from 1974 to 1978, and since 1992 a dedicated foundation has run it as a museum.

A thousand years ago this coast belonged to Tapuia peoples, who moved inland as Tupi groups arrived from the Amazon. By the time the first Europeans landed in the sixteenth century, the mouth of the Paraíba marked a frontier: the Potiguara held the country to the north, the Tabajara the country to the south. Colonisation drove a wedge straight into that line. The Tabajara allied with the Portuguese; the Potiguara became their most determined opponents and fought them for decades. Both choices were made by people reading a bad situation as clearly as they could, and neither ultimately protected them from what the fort at the river mouth was built to make possible.

The modern reason Cabedelo exists at the scale it does is the port. A federal decree authorised it in 1905, construction started in 1908, the first 178 metres of dock were standing by 1917, work stalled, resumed in 1932, and the Port of Cabedelo finally opened on 23 January 1935. Today the quay runs 602 metres and takes six to nine ships at a time, with an access channel dredged to 9.14 metres in 2011 and roughly 17,000 square metres of warehouse behind it. Petroleum derivatives dominate the traffic, followed by wheat and petcoke, and the port feeds fuel out across the Northeast. Its real selling point is a map: of all Brazilian ports, this is the one closest to Africa and Europe. The trade sustains the richest municipality in Paraíba by output per head.

At kilometre 8 of the BR-230, the road drops to Praia do Jacaré — an estuarine beach on the Paraíba side, named for the caimans that once crowded the river mouth. The water here is river and sea mixed, and swimming is often a bad idea, but nobody comes for the swimming. They come at the end of the afternoon, take a table facing west across the estuary, and wait. As the sun goes down a saxophonist plays Ravel's Boléro — a performance repeated at sunset more than four thousand times, until the ritual became the single thing Cabedelo is known for outside Paraíba. The piece runs about fifteen minutes and builds the whole way. So does the light.

Offshore, Areia Vermelha surfaces only at low tide — a sandbank that appears, fills with day-trippers, and drowns again, protected as a marine state park since 28 August 2000. Inland the 103-hectare Restinga de Cabedelo National Forest, created in 2004, holds a fragment of the coastal scrub that once covered the whole spit. Cabedelo's own status has been almost as tidal. It won autonomy under Law 283 of 17 March 1908, lost it in 1928 when the capital absorbed its territory, reappeared as a district of João Pessoa in a 1933 reorganisation, and was finally restored as a municipality by State Law 1631 of 12 December 1956, installed on 31 January 1957. Four times in fifty years the spit was told what it was.