Lincoln County in ME is first with 3.5%.
Incidentally, neither has low employment. Neither is a retirement destination. Neither has decades-long substantial child poverty. Both got worse or bottomed out on all the obesity and diabetes change metrics (4 of these; each county needs at least 3 with actual values to qualify).beat
Sagadahoc County in ME (4.1%),
Cumberland County in ME (4.5%),
Oxford County in ME (4.7%),
Franklin County in ME (5.2%), and
Knox County in ME (5.4%), and 9 others, ending with
Piscataquis County in ME (6.8%).