The way residents register to vote has changed, following the biggest change to the electoral registration system in nearly 100 years.
The Individual Electoral Registration will require each member of a household to register to vote.
Under the old system, the 'head of household' could register everyone who lived at their address.
Most people will be transferred to the new register automatically as their details will be matched against records held by the Department of Work and Pensions (DWP).
However, 7,200 residents in St Albans were told that they need to take action by registering on the electoral register so that they can vote.
Mike Lovelady, the electoral registration officer for St Albans District Council said: "Residents should have recently received a letter from the council telling them whether they have been automatically registered on the new electoral register.
"If they are not on the register, then they need to take action. They can register to vote online at www.gov.uk/register-to-vote or by contacting the Council’s Electoral Services team."
If residents have not received a letter from St Albans City and District Council, they should contact the electoral services team by calling 01727 819294 or emailing email@example.com.