The Online Etymology Dictionary says
uppity was "originally used by blacks of other blacks felt to be too self-assertive (first recorded use is in "Uncle Remus"). The parallel British variant
uppish (1670s) originally meant "lavish;" the sense of "conceited, arrogant" being first recorded 1734."
the OED Online says
uppity means "Above oneself, self-important, ‘jumped-up’; arrogant, haughty, pert, putting on airs," and attests it from 1880:
quote:
1880 J. C. Harris Uncle Remus: Songs & Sayings 86 Hit wuz wunner deze yer uppity little Jack Sparrers, I speck.
The word in itself is not racist, but when used by whites disparagingly against blacks it becomes racist, as in the following quote (from The OED Online):
quote:
1952 F. L. Allen Big Change ii. viii. 130 The effect of the automobile revolution was especially noticeable in the South, where one began to hear whites complaining about ‘uppity niggers’ on the highways, where there was no Jim Crow.
It's similar to the word
boy, a perfectly good word with no racial connotations; but when it is used in a demeaning manner by whites against blacks it becomes racist.