Final answer:
Skilled workers were forbidden to leave Britain in the late 18th and early 19th centuries to maintain Britain's economic advantage by preventing the spread of industrial knowledge to potential competitors, such as the United States.
Step-by-step explanation:
Skilled workers were forbidden to leave Britain during the late 1790s and early 1800s because the British government wanted to prevent the spread of industrial knowledge and protect its economic dominance, specifically in the advanced textile industry. Britain, during this time, had the most advanced textile mills and machines in the world and wanted to maintain its economic advantage over the United States, which relied on Britain for finished goods. To secure this advantage, Britain implemented a ban on the emigration of skilled workers - mechanics who knew how to build and repair the latest textile machinery, thus preventing the transfer of this technical knowledge to other countries that could become competitors.