Sugar was long the mainstay of the economy, but its importance declined dramatically in the late 20th century.
Its commercial importance declined with the development by the Iranian government in the 1960s and '70s of Khorramshahr as the principal port for the Persian Gulf.
The colony prospered as the seat of government of the Spanish possessions in the Americas until the conquest of Mexico and Peru, after which its importance declined.
The port's importance declined with the opening of a rail line between Matsuyama and Takamatsu (stopping at Kotohira) in 1889 and with the subsequent development of bus and then air service linking Kotohira with major cities.
Rostock was extensively developed after World War II as East Germany's principal ocean port; since the reunification of East and West Germany, however, the harbour's relative importance declined as other ports (notably Hamburg) recovered their historic trade areas.
Its importance declined with the transfer of the Northwest Territories to Canada in 1870 and the establishment in 1931 of the transcontinental railroad's branch line to Churchill on Hudson Bay, 140 miles (225 km) northwest.
Caerphilly Castle, another of the county's many castles, was built in 1271 to counter a threat to English rule in Glamorgan by Llywelyn ap Gruffudd, the only Welsh ruler that the English officially recognized as prince of Wales; its importance declined a few years later, however, with the loss of Welsh independence in 1283.
Renamed for the Natchitoches Indians (members of the Caddo confederacy), it developed as a cotton market, but its commercial importance declined after 1825, when the Red River, then its main artery of transportation, changed course, shifting 5 miles (8 km) to the east.
With the reorganization of the central administration in 1954, his importance declined, and in 1956 he was made an alternate rather than a full member of the Politburo, although he continued to be linked with the government's intelligence and security operations.
BOHs generally had greater amino acid concentrations than the surrounding mineral horizons in both successional stages, but amino acid concentrations in successive BOHs declined with depth in the soil profile, suggesting that although BOHs do remain as biological hot spots and potential nutrient reservoirs as far down as 60 cm depth, their importance declines over time.
