In the state of Texas USA why are some offenses of DWI misdemeanors and others felonies?

Broadly speaking there are two reasons that a DWI felony might be charged instead of a DWI misdemeanor in the state of Texas. The first is if the offender has caused injury or death to another person while intoxicated. The second is if the offender has previous convictions for DWI and fits one of several other conditions. Basically, DWI felonies are reserved for those that do harm to others or are repeat offenders.