PORTSMOUTH — Former Planning Board and Historic District Commission member William Gladhill wants city officials to think about one thing in particular “every time you make a decision.”

Gladhill, in his resignation letter from the two boards, referenced his mentor former City Councilor John Hynes who frequently asked, “How big can Portsmouth get while still being Portsmouth.”

That question, Gladhill said, “was always with me whenever I had to make a policy decision.”

Gladhill, in an interview Saturday, noted that Hynes “never provided an answer” to the question about how big Portsmouth can get while still being Portsmouth.

“To be honest it’s one of the questions you have to ask yourself, but is there a real answer to it,” Gladhill said. “If you answer yes what do you do, you can’t stop development, you just can’t. I wanted it to be smart growth.”

Gladhill — who voted to approve the controversial Portwalk 3 downtown development and North End Portsmouth — said he has learned that New Hampshire is a “very strong property rights state.”

For example, if a developer proposes a major project in some other states, the land-use boards can require that a certain number of those condominiums or units be work-force or affordable housing.

The lack of affordable housing in Portsmouth is something else Gladhill addressed in his resignation letter.

“The state of New Hampshire doesn’t allow that,” Gladhill said about requiring a certain number of units of affordable or work-force housing. “We can suggest that as a land-use board, but we can’t enforce it.”

He also noted that what people sometimes don’t understand is if a project meets the zoning requirements “it’s very difficult to reject something just because you don’t like it.”

Gladhill pointed to complaints by some developers that land-use boards take too long to review projects.

“In Portsmouth that’s a good thing, it shows we are taking our time and getting things right the first time,” Gladhill said.”I never looked at timelines when we were reviewing projects.”

Gladhill, who is moving to York, Maine, with his family, said he does not see an easy solution to the lack of affordable housing in Portsmouth.

“We have a city where land is very expensive and it’s a desirable place to live,” Gladhill said. “It’s supply and demand, it’s basic economics.”

Ideas like building micro apartments could serve singles or young couples, but it won’t help “a young couple who are getting married and raising a family,” Gladhill said.

Because there’s less and less land to develop in Portsmouth, Gladhill believes when something is developed “those are not going to the affordable market.”

“If a developer can get a higher price that’s what they’re going to do,” Gladhill said.

Gladhill, who was born and grew up in Portsmouth, said he remembers the price of housing starting to rise in Portsmouth and the entire Seacoast in the early 1990s.

“There was a trend of people moving into southern New Hampshire and Southern Maine as more people wanted to move here because they saw it as a desirable place to live,” Gladhill said. “That’s what drove prices up.”

Gladhill called his family’s move to York “not an easy decision.”

His wife, whose family has lived in York since the 1650s, grew up in York and they saw a property in York that they liked and decided “why not take a chance.”

“The price was right for us and Portsmouth is a very expensive town. I would have a hard time affording a place in Portsmouth that we were able to afford in York,” Gladhill said.

But despite his family’s move out of his hometown and the concerns he raised in his resignation letter, Gladhill says he remains optimistic about Portsmouth’s future.

“I think the good thing about Portsmouth is I love how citizens get out and speak in front of the boards,” Gladhill said. “As long as the citizens stay involved, I’ll remain very optimistic.”