The vast majority of sex offences in the US are non-repetitive, and sex crimes have the lowest rates of recidivism.
The Mercado and colleagues 2013 study showed that only 5% of convicted offenders committed a new sex crime in 6.5 years.
Since the Registry opens a great potential for new felonies (specific to SOs) such as "failure to register", "loitering in a protected area", and "contact with another offender", general recidivism for SOs is forced higher.
This coupled with the fact that offenders on the registry are more likely to be denied housing and work can make crime the only avenue for survival.
These struggles push the general (non-sex crime) recidivism rate for SOs to 28%.
HOWEVER, 5% sexual re-offense and 28% general crime recidivism for sex offenders is remarkably low when compared to:
Assault - 59.6%
Burglary - 62.2%
Murder - 52%
And yet, sex offenders are the only group subject to the registry.