The New Zealand stock operator has been registered as a Foreign Board of Trade by the American regulatory agency, the Commodity Futures Trading Commission (CFTC).
The move means customers in the US can take part in trading on the stock operator's Dairy Derivatives platform, which they had not previously been able to do.
The NZX offers trading in whole milk powder, skim milk powder and anhydrous milk fat futures.
Dairy Derivatives launched three years ago and grew by 52 percent last year.
NZX head of derivatives Kathryn Jaggard said she expected growth to be at about the same rate this year.
"What we're looking for more than anything is additional participation, so more accredited participants coming into the market, and that will certainly help with liquidity," Ms Jaggard said.
Participation was expected to come from growth in South-East Asia, the US due to the CFTC approval making access easier, and Europe because the trading hours are more day-time friendly there, she said.
"What the greater participation does is, essentially, increase liquidity. The more participants you have, the more divergence of opinion you have, and so therefore the more trading you have.
"Any futures contract depends on liquidity to continue its forward growth. That liquidity means, for NZX, a greater number of lots traded and for New Zealand it means that New Zealand becomes essentially, hopefully, the home of the financially traded markets in dairy commodities, which for New Zealand is really important."
New Zealand was dominant in terms of the physical trade of dairy commodities and it was important it continued to grow in terms of its place in the world in the financial trade for dairy, Ms Jaggard said.