That is the highest share in Central Florida and 3.5 percentage points above Florida's 15.9% rate.
The rate has recovered 3.5 percentage points from its 55.6% low after the housing bust, while the share of cost-burdened households has edged up from its low.
That trails the U.S. share of 3.2% and is close to Florida's 1.2%, while 68.1% of county workers drive alone, census estimates show.
Seniors make up 39.5% of the county's veterans, compared with 35.2% in Bexar County, a gap of 4.3 percentage points.
Education, health care and social assistance employ 19.6% of working residents, ahead of the 16.3% in hotels, food service and entertainment.
42.7% of Seminole County adults hold a bachelor's degree or more, compared with 27.8% in Lake County next door.
