What makes Central America a region

The isthmus, and the two coasts

Belize is the member with no Pacific shore and El Salvador the member with no Caribbean one. Everywhere else along the isthmus a country holds a piece of both, and the ground between the two is narrow enough that it has been treated as a crossing for as long as it has been surveyed. The Panama Canal opened on 15 August 1914 across about 80 kilometres of it. The Canal Zone was administered from Washington until the treaties signed on 7 September 1977 set a date, and the waterway passed to Panama on 31 December 1999.

Six of the countries keep a single clock at UTC-06:00. Panama keeps UTC-05:00, which puts a one hour step at the Costa Rican border.

What the ground does

The volcanic front stands inland of the Middle America Trench, along the line where the Cocos Plate goes down beneath the Caribbean Plate, and the volcanoes run behind the Pacific coast from western Guatemala into Costa Rica. Guatemala's high point is one of them, Volcán Tajumulco at 4,203 metres. The country carries a second plate boundary as well: the Motagua fault, dividing the Caribbean Plate from the North American one, which produced the earthquake of 4 February 1976, recorded at magnitude 7.5 near Los Amates.

Belize sits off the arc. Its ground is limestone, and Doyle's Delight in the Maya Mountains reaches 1,124 metres.

Capitals that moved

Twice on this isthmus a capital has been abandoned rather than repaired. The Santa Marta earthquake of 29 July 1773 wrecked Santiago de los Caballeros, and the Spanish crown moved the seat of the captaincy general to a new site founded in 1776, which is the present Guatemala City; the older town kept the name Antigua Guatemala. Hurricane Hattie came ashore at Belize City on 31 October 1961. Building of an inland replacement began in 1967 up the Belize River valley, the government moved to Belmopan in 1970, and Belize City kept the port.

One state, then several

Annexation to the Mexican Empire followed the act of 1821 and lasted about a year. The Federal Republic of Central America was declared on 1 July 1823 and came apart by secession: Nicaragua in April 1838, Honduras and Costa Rica later the same year, Guatemala in April 1839, and El Salvador declaring itself a separate republic on 2 February 1841, which is the date its record still carries. Panama was a department of Colombia until 3 November 1903. Belize was administered as a British colony until independence on 21 September 1981, and its official language is English while Spanish is official in the other six.

The federal flag survives on the map. El Salvador, Honduras and Nicaragua kept the blue and white bands horizontal, Guatemala turned them vertical in 1871, and Costa Rica added a red band on 29 September 1848.

Where the edges are argued

The M49 standard published by the UN Statistics Division files Mexico in Central America alongside the countries here, and states that its groupings are a statistical convenience carrying no political meaning. The Central American Integration System, created by the Tegucigalpa Protocol of 13 December 1991, runs the other way: Belize acceded in 2000 and the Dominican Republic became a full member in 2013, which makes the group wider than the isthmus on one side and later than it on the other. The Central American Parliament seats members from Guatemala, El Salvador, Honduras, Nicaragua, Panama and the Dominican Republic, and Costa Rica has never ratified.

One boundary inside the group is before a court. Guatemala's claim to Belizean territory went to referendum in Guatemala on 15 April 2018 and in Belize on 8 May 2019, and the International Court of Justice was seised of it on 12 June 2019. The catalogue records the claim and the proceedings, and settles neither.