Is the unemployment office open the day after Christmas?

Technically the day after Thanksgiving is not a federal holiday, so in some situations unemployment offices may be open the day after Thanksgiving. The bottom line is, this will vary from state to state, as unemployment is a state administrated benefit regulated by the states individually. I can say that in Washington state, however, they are closed. Many other states will likely be closed after Thanksgiving either as an added bonus for their employees, or as a cost-cutting measure.

To get a definite answer for your particular state I would suggest searching your state's website, but it is likely they will be closed.