Illegal Entry by Deported Aliens - any alien who has been denied admission, excluded, deported, or removed or has departed the United States while an order of exclusion, deportation, or removal is outstanding, and thereafter enters, attempts to enter, or is at any time found in, the United States, unless prior to his re-embarkation at a place outside the United States or his application for admission from foreign contiguous territory, the Attorney General has expressly consented to such alien's reapplying for admission; or with respect to an alien previously denied admission and removed; shall be fined or imprisoned not more than 2 years, or both.
Source: http://www.law.cornell.edu/uscode/text/8/1326
Source: http://www.law.cornell.edu/uscode/text/8/1326