The place that launched 1,000 ships

The Panama Canal has seen a lot of water pass through its locks. It's one of the great fault lines of modern history, a place where north meets south and dreams evaporate in the heat

As the truck whooshed past, the bridge shook in the manner that bridges do when they are on the point of collapse. Next, the horizon disappeared behind a foul mushroom cloud of exhaust fumes. The walkway was so narrow I had to spreadeagle flat against the thin wire mesh that is supposed to protect people from tumbling 100m to the water below. (The purpose, whispered one local, was to prevent homicides, not suicides.) But I pressed on, determined properly to survey the gash that splits North America from South.

As the truck whooshed past, the bridge shook in the manner that bridges do when they are on the point of collapse. Next, the horizon disappeared behind a foul mushroom cloud of exhaust fumes. The walkway was so narrow I had to spreadeagle flat against the thin wire mesh that is supposed to protect people from tumbling 100m to the water below. (The purpose, whispered one local, was to prevent homicides, not suicides.) But I pressed on, determined properly to survey the gash that splits North America from South.

The Golden Gate Bridge may be more elegant, famous and durable, not to mention more pleasurable to walk across, but only the Puente de las Americas can claim to bind the two halves of the continent together. This wobbly steel assembly bears Central America's Main Street - the Pan-American Highway - over the Panama Canal. The greatest road on the planet crossing the mightiest canal in the world. So you can hardly expect it to be fun.

The highway is no mean achievement: when 21 nations gathered in Buenos Aires in 1936, they sparked the construction of a road that would stretch 24,000km from Fairbanks, Alaska to Tierra del Fuego in Argentina. Or, rather, they strung together a lot of existing roads and built a few extra links to connect them. The small matter remains of a 120km stretch through the Darien Gap between Panama and Colombia that is marked on maps as en proyecto, though there is little enthusiasm for the project on either side.

No such gaps obstruct the Panama Canal between the Atlantic and Pacific oceans. When it opened on 15 August 1914, the Canal Interoceanico was the greatest human construction ever undertaken - and the culmination of a plan that Charles V of Spain first hatched in 1534, when he ordered a survey for a proposed canal across the narrowest point in the Americas.

Panama's unique claim to geographic fame was first recognised in 1513, when Vasco Nunez de Balboa led a straggling band of Spanish colonists from the Atlantic across to the Pacific. It took him 27 days, and he was beheaded shortly afterwards. (You can make the journey in an hour and a half on a bus - and enjoy a rather longer life expectancy.)

Ghostly evidence of past dreams is on show at the shiny new Panama Canal Museum in the capital. It reveals the tortured story about the elimination of other candidates. Nicaragua had the strongest claim: for much of the 19th century, Central America's largest country had provided the fastest way to travel between the East and West coasts of the US. Political subterfuge, aided by worries about geological stability, steered investors to make the incision further east, along a path of greater resistance (including the need to cut through the 100m-high Continental Divide) but, it was believed, calmer tectonics.

The first serious attempt was made by the French. Ferdinand de Lesseps, the man whose Suez Canal had connected the Mediterranean and Red Seas, began work in 1881. Eleven years and 22,000 deaths later, the project went bankrupt. The Americans believed they could pick up the pieces - once they had solved a political problem, which was that the entire isthmus belonged to Colombia, which neither then nor now enjoyed cordial relations with Washington. Geo-political manoeuvring prised away from Colombia a slice of territory the size of Scotland. Panama's new government invited in the US.

Out went the peso, in came the balboa, named after the first European to sight the Pacific. But the national currency turned out to be nothing more than the US dollar. Along with it came 75,000 labourers, to create a channel 80km long and 100m wide.

The Channel Tunnel represents a mere splinter beneath the surface of the earth compared with the deep scar which the canal has carved through Central America. The earth removed would be enough to build 63 Great Pyramids. And, for every three metres of the canal, one worker died.

To protect the $352m investment ($23m under budget), the Americans took over a belt of land on either side of the canal, a buffer between the waterway and tropical jungle. Towns were built in the Panama Canal Zone to cater for engineers and servicemen. Today, strewn along the canal you find pockets of abandoned small-town America. A watchtower in one slice of suburbia bears the succinct message "It's all yours, suckers", painted last December when the canal was finally handed over to the country through which it runs.

You need not sail the canal to appreciate the canal; a series of vantage points provides superb views. After Puente de las Americas, where the canal spills into the Pacific, you can hop on a cheap, cheerful bus to Miraflores Locks - a symphony of concrete, steel and water - where a slick presentation tells the history of the waterway. From a grandstand, you watch the painful process of guiding a freighter through a lock with just a few centimetres to spare. While this spectacle unfolds, a tour guide bombards you with figures. In its 86 years, you learn, the "Big Ditch" has carried 800,000 vessels. Fees are calculated according to displacement; the lowest was 36 cents, paid in 1928 by a lone swimmer who paddled from one ocean to the other.

The average ship pays $32,000 - sorry, 32,000 balboas - for what is described as a "quality transit service". What you are not told is that obsolescence set in as early as 1936, when the Queen Mary became the first vessel too big to fit through the canal. Yet the Panamanians have set about nurturing the artery as though life depends on it; for many of them, it does. The Zone has been energetically transformed, with officers' quarters and look-out posts turned into luxurious resorts where you can experience the wonderful, enveloping feeling of being embraced by rainforest.

One blight on the landscape is Colón, at the Atlantic end of the canal. This worn-out port looks like the set for some particularly grisly post-apocalypse movie - except for the high-walled Duty-Free Zone, where cut-price watches are sold to cruise passengers. On the far side of the tracks that once belonged to the trans-isthmian railway, you reach Cristóbal, another town populated with US ghosts, though with spirits still alive at the yacht club where skippers and crew gather. You can sign up here to act as linehandler on a transit through the canal. Or just sit back, sip a Soberana (the splendidly named local beer) and enjoy the sunset. A kink in the Americas twists Panama so that the Atlantic entrance of the canal is actually west of the Pacific end, and makes this the one place on the Atlantic to watch the sun plunge into the ocean.

Getting there

Simon Calder is the author of 'Panamericana: On the Road through Mexico and Central America' (Vacation Work, £12.95). He paid £408 for a flight from Gatwick via Houston to Panama City on Continental, and $30 (£21) a night at the Hotel Covadonga in Panama City . Recommended reading: 'The Path Between the Seas' by David McCullough (Pocket Books, £12.99)