In 1827, Sultan Said sailed from Muscat to Zanzibar to inspect his far-flung territory. Here he met one Edmund Roberts, an American merchant from Portsmouth, New Hampshire, who suggested a commercial treaty between Said and America. Soon Zanzibar was supplying large amounts of ivory to America and western Europe. African ivory was soft and easy to carve into combs, piano keys and billiard balls. Asian ivory, in contrast, was hard and brittle. (So great was the American demand for ivory in the 1830s that a town called Ivoryton was established in Connecticut, with a factory making piano keys and billiard balls out of ivory imported from Zanzibar.) The Americans also purchased animal hides and gum-copal, a tree resin used in the manufacture of varnish. In return, cotton cloth (called 'Amerikani'), guns and gunpowder were imported into Zanzibar for distribution along the coast and to Arabia.

Sultan Said realised that trade with Europe and America would increase Zanzibar's wealth and strength, and thereby consolidate his own position, so at the end of the 1820s he decided to develop Zanzibar's clove industry further. His first move was to confiscate the plantations of Saleh bin Haramil al Abray, who had introduced cloves to the island in 1812. Said's reason for this was that Saleh was the leader of a political faction competing for power, and had also continued to send slaves to the Mascarenes after the Moresby treaty had made this illegal.

Vast plantations were established on Zanzibar and Pemba, and the islands' prosperity soon grew dramatically. Said decreed that three clove trees must be planted for every coconut palm, and that any landowner failing to do so would have his property confiscated. He became the owner of 45 plantations scattered over the island, with about 50 slaves working as labourers on the smaller plots and up to 500 on the larger ones. Cloves fetched a high price abroad and by the end of Said's reign Zanzibar was one of the world's leading clove producers.

Said valued Zanzibar's large harbour, abundant freshwater supply and fertile soil. He also recognised the strategic importance of a Busaidi power base on the east African coast, and decided to spend several months on the island each year. A large house was built for him at Mtoni, on the west coast of the island about 5km north of Zanzibar Town.

Over the next few years, Said came under increased pressure from the British to abolish slavery. This call was strengthened in 1833, when the Emancipation Act abolished slavery throughout the British Empire and all slaves in British territories were freed. Recognising the need for strong allies, in the same year Said formalised the trade agreement suggested earlier by Edmund Roberts and signed a Treaty of Amity and Commerce with the United States of America. This gave the Americans freedom to set up trading posts at Zanzibar and on the mainland. In return, Said hoped for armed assistance against the Mazrui and for British anti-slavery pressure to ease. In 1837 Said finally managed to oust the Mazrui from Mombasa and install his own garrison of soldiers in Fort Jesus. His presence along the coast of east Africa was finally complete.

Links between Zanzibar and America became increasingly cordial, and a consul, Richard Waters, was appointed in March 1837. Said presented him with a horse and a boat, and Waters was often the sultan's guest at Mtoni Palace. In November 1839 Said sent his trading ship El-Sultani to America. The ship arrived in New York in May 1840, the first Arab boat ever to visit an American port, and returned to Zanzibar with a cargo of arms and ammunition, china, beads and 'Amerikani' cloth.