500
They were invented in 1853 by a Native American/African-American hotel chef who wanted to mollify a guest who kept complaining that the fried potatoes were too thick and soft.
What are potato chips? (George Crum wanted to teach the complaining guest a lesson, so he sliced potatoes as thin as possible, fried them until they were brittle, then added too much salt. The potatoes were a huge hit, but being African American, Crum couldn't take out a patent on his invention.)