What's the origin of the phrase "around the horn"?

Yesterday as we were sitting in traffic, my husband said he would have gone "around the horn" had he known traffic was so bad, meaning to take a longer way. What is the derivation of this phrase?

Solution 1:

"Around the Horn" has always referred to Cape Horn, but it's only since the existence of the Panama Canal that it has been "the longer way". With modern ships it's not the danger it was in the days of sail, but it would still be a very expensive detour in many cases.

Solution 2:

It originally referred to sailing around Cape Horn (at the southern tip of South America), which was a long and dangerous journey.

According to The Encyclopedia of Word and Phrase Origins,

In the days of the tall ships any sailor who had sailed around Cape Horn was entitled to spit to windward; otherwise, it was a serious infraction of nautical rules of conduct. Thus, the permissible practice of spitting to windward was called 'round the horn.' Cape Horn isn't so named because it is shaped like a horn. Captain Schouten, the Dutch navigator who first rounded it in 1616, named it after Hoorn, his birthplace in northern Holland.