A group of the country's top infrastructure leaders have flown to the US, seeking answers to pressing transport and housing problems.

Forty-two people, from various Government ministries, councils and Infrastructure New Zealand travelled to Portland, Houston, Dallas and Denver.

Infrastructure New Zealand head, Stephen Selwood, says they found a big contrast between the high-cost, but more developed city of Portland, with the low-cost, sprawling Houston.

He says they saw houses built for less than $300,000 in Houston which would sell for a million in Auckland.

"The question we were asking is, is there some sort of half way house where we can get the livable, smart city of Portland with the affordable housing of Houston and that was the objective."