There were three county council seats within the Welwyn Hatfield area in 2017, each won by a different party, with a margin of fewer than 100 votes.
The Lib Dems won the Haldens seat with 1,595, just 98 more votes than polled by the Conservatives.
In Hatfield East the Conservatives won with 1,078 votes - which was 98 more than Labour, and in Welwyn Garden City South Labour won the seat with 1,403 votes - just 71 more than the Conservatives.
Meanwhile all seven county council seats in Hertsmere are being contested by Conservative, Green, Labour and Liberal Democrat parties.
In addition there are candidates from Trade Unionists and Socialists Against Cuts (Borehamwood North), UKIP (Borehamwood South) and independent candidate Rosemary Gilligan (Potters Bar West and Shenley).