Wanganui will know tomorrow whether an H is going to be inserted in its name.

Land Information Minister Maurice Williamson has been pondering the question for several weeks and will announce his decision in Wanganui at 11.30am tomorrow.

The New Zealand Geographic Board decided earlier this year that the spelling should be changed to the Maori version, Whanganui, but locals voted four to one against.

Mr Williamson is the ultimate decision-maker and will brief Wanganui Mayor Michael Laws an hour before the announcement.

Mr Laws said it would be a huge day for the city because the New Zealand Rugby Union was also going to announce the host cities for the 2011 Rugby World Cup.

He said he didn't know anything about either decision.

"I am appreciative of the fact that Maurice Williamson is actually coming to Wanganui to make that decision. He is doing it in person, fronting up, and not leaving it to a press secretary to relay," Mr Laws said.

"Obviously it is the desire of Wanganui people that their democratic decision - made by referenda in both 2006 and 2009 - is upheld.

"Locals voted four to one in favour of retaining our name, mana and identity."

Mr Laws said the council left no stone unturned in its efforts to retain the name.

"We commissioned an independent history, consulted the community and researched the implications," he said.

"We believe the NZ Geographic Board to be wrong in both fact and logic."