[In many states today DWI is a felony.]
Can you provide proof? I would like to know which ones. I believe most are misdemeanors or, in some, petty offenses.
Right, it is usually a misdemeanor absent aggravating factors such as previous conviction, causing accident with injury, endangering a minor, drag racing, etc., per Law Summary here.
(The summary glosses over any distinction between DUI and DWI, but some states have DWI as a more serious charge such as DUI being blood alcohol level BAL of .08 and DWI being, for example, a BAL of .15 or higher. Other states just use one term or the other (DUI and DWI) and don't make such a distinction.)
In New Hampshire, the charge of 30 miles or more over the limit when DWI makes it aggravated DWI, but it is not a felony unless there is an accident with serious bodily injury. Consider New Hampshire Laws Section 265-A:3 with penalties part at Section 265-A:18 by shown here.