Sixteen and 17-year-olds look set to vote in council elections as part of the biggest changes to Wales' voting system in 50 years. Legislation, to be introduced to the assembly on Monday, would also allow resident foreign nationals to vote.
And there are plans to give prisoners serving sentences of less than four years local votes. Local Government Minister Julie James said the legislation was about reinvigorating local democracy.
The voting age reduced across the UK from 21 to 18 in 1969. In Scotland, 16 and 17-year-olds are already able to vote in local and Scottish elections. It is estimated lowering the voting age to 16 would add around 75,000 people to Wales' electoral roll.
Extending it to all resident foreign nationals would add some 33,000 at the next local elections in May 2022, based on 2018 Office for National Statistics data.
Around 1,900 prisoners would also gain the vote, in line with the recommendations of the assembly's equality committee.
The Welsh Government's wide-ranging plans for the 22 local authorities include:
Ms James said Welsh ministers believe in strong local government and want it to thrive.
Twenty years on from devolution, this is a significant local government bill which reflects the journey of devolution and will deliver a major package of reforms, including local government electoral reform, she said.
It aims to provide local government with new ways to support and serve their communities in these challenging times, while reinvigorating local democracy here in Wales.
The legislation - called the Local Government and Elections (Wales) Bill - is being introduced before the assembly after being developed over five years.