Today I found out the origin of superstitions surrounding black cats including why a black cat crossing your path is considered bad luck.

…In fact, in early Egyptian times, dating back as far as 3000 BC, cats (including black ones) were the rock stars of the animal world…The hysteria of witches practicing black magic had just hit Europe and alley cats were often cared for and fed by the poor lonely old ladies …later accused of witchery.

Their cat companions, some of which were black ones, were deemed guilty of witchery by association. This belief was taken up a notch when a folklore involving a father and son in Lincolnshire in the 1560’s started making the rounds. The pair were said to have been traveling one moonless night when a black cat crossed their path and dove into a crawl space. …they threw rocks at the furry feline until the helpless injured creature scurried out into a woman’s house, who at the time was suspected of being a witch.  The next day, the father and son came across the same woman and noticed she was limping and bruised and believed that to be more than just a coincidence. From that day on in Lincolnshire, it was thought that witches could turn into black cats at night.

However, in some cultures, the black cat is still revered and a symbol of good luck even today…

Source: Why Black Cats Are Considered Bad Luck