Jail isn't prison. Your post specified "prison." Only a person convicted of a felony can go to prison.
Additionally, I don't know which jurisdiction you copied that from, but classifications of misdemeanors and their potential sentencing ranges vary by state. While a misdemeanor can never merit more than one year in jail, some jurisdictions cap jail time at 6 months (to limit a defendant's right to a jury trial) and some may jail time possible for even the lowest level misdemeanor. For example, in my jurisdiction a class 3 misdemeanor (the lowest level or "petty" misdemeanor) is still punishable by up to thirty days in jail. Hence, in my jurisdiction a person can do thirty days by merely tapping somebody on the shoulder who didn't want to be tapped on the shoulder.
See why creating federal legislation to determine deportation can get difficult? Simply saying "any crime" or any crime where jail is possible is far too overreaching/harsh. In contrast, a felony conviction may not get "rid" of the undocumented immigrants our federal government would want to get rid of (i.e. a habitual drunk driver, a domestic batterer, a thief, etc).
Hence why this #### gets completed and there are 120+ page charts for lawyers and judges to use to determine whether a person should be deported.