Two nooses were found hanging at high schools in Los Angeles County on Oct. 15 and 16. At Bellflower High, the hangman's knot was accompanied by graffiti declaring that God hates black people. At nearby Mayfair High, the noose wasn't captioned, and a Sheriff's Department sergeant told The Times, "A noose in itself is not making any correlation to anything."

But is that ever true?

The hangman's knot, a rope looped and secured with multiple wrapping turns or coils, probably was adapted from knots used in horseback riding, fishing and sailing. It looks a lot like a heaving-line knot, used by sailors to add weight to a rope thrown from boat to shore. Whatever its derivation, it was ultimately put to use hanging humans by the neck until they were dead.

Hanging has been a method of execution for thousands of years. In colonial America, on the Western frontier and well into contemporary times, records show that at least 9,324 people have been hanged legally in this country. In 1996, Billy Bailey of Delaware became the last to be executed by hanging.

The majority of those hanged, or executed by any means, were poor and racial or ethnic minorities. Of the approximately 15,000 people executed in all in this country, from 1608 to 2002, the top three occupations were slave, laborer and farmhand; 11% were slaves...