I've been playing around with the free access to the 1930 census on Footnote.com and in experimenting with their interface, I remembered something:
anyone can easily be listed twice in the census.
My Grandma is listed twice in 1930--once with her parents and once in the household where she was "working out."
Her married brother is listed twice as well. Once with his wife in the town where he grew up and once in the town 30 miles away where he and his wife had moved for his job.
Never hurts to look more than once.
And if you think "working out" means exercise, well....it doesn't.
Note: the free access to the 1930 census on Footnote.com is only for the month of August 2009.