Why did Gibraltar not develop into a thriving trade city like Singapore? It appears to be located in a very favorable place, at the head of the Mediterranean and along one of the world's major trading routes.
Size.
Gibraltar is quite literally a rock (although one that's been tunneled into rather extensively) with a tiny area, much of which is fill, outside the rock that's a town of 30,000. The entire area of Gib, including the Rock, is 2.3 square miles (6.0 square kilometers), and Spain is immediately on the other side of the border. You can see the marina in this picture, just north (upward) of the Gibraltar airfield, that marks the Spanish border line. In addition, many of the roads on Gibraltar and much of the land is controlled directly by the British military, which means that the already limited space for commerce is further limited. The city has a population density of about 12,000 people per square mile. Singapore, by contrast, is an island of about 277 square miles, supporting a population of 5.5 million.
