The airline, which offered return fares from Â£203, will drop Providence, Rhode Island in October after axing Bradley in Connecticut last month.
Its remaining transatlantic route from Edinburgh, to Stewart, 60 miles north of New York City, was also reduced from daily to four flights a week from March.
The Providence flights were cut from five to three a week.
Norwegian, which competes with three other airlines flying between the capital and New York, initially blamed lack of demand for the latest cutback.
However, it later attributed the move to the Scottish Government shelving a planned halving of air passenger duty (APD) - which the previous route axe was blamed on.
Norwegian is also suspending Providence flights from Cork and Shannon in Ireland, where APD is not charged.
It said the drop in demand was no lower on the Edinburgh than the Irish routes.
Scottish ministers had hoped to cut APD by 50 per cent this month, reducing the charge per passenger on flights to the US from Â£75 to around Â£37.50.
However, they postponed the move because of the need to win EU approval for continued APD exemption for Inverness.
Aviation analyst John Strickland, of JLS Consulting, said: "APD will have contributed to the decision, but a number of new, smaller, secondary markets have yet to prove themselves.
"Traffic is likely to be more price sensitive on some of these routes, but pronounced seasonality is also a challenge, regardless of price levels "
A spokesperson for Norwegian initially said today: “Following a comprehensive review of our services, we have decided to suspend flights from Edinburgh, Cork and Shannon to Providence during the quieter winter period due to lower demand."
However, this was later "updated" to: “Following a comprehensive review of our services, we have decided to suspend some routes during the winter season, including Edinburgh-Providence.
"Flights from Scotland continue to bear the full brunt of the UK’s APD which has demonstrably been dampening demand, particularly in the quieter winter months.
"We therefore urge the Scottish Government to quickly resurrect plans for a reduction in air passenger taxes which could re-open the door to more flights and lower fares for passengers and a boost to Scotland’s connectivity.
"We still see potential at Edinburgh and our Providence route will continue through October and we will continue to assess our transatlantic route performance as we confirm the route schedule for summer 2019.”
A spokesman for Edinburgh Airport said: “We shouldn’t be surprised at the lower demand on these services when Scotland’s aviation taxation is amongst the highest in the world.
“The Scottish Government must act now to deliver on its promise to Scottish passengers – cut the tax, grow Scotland’s links to the world and boost the substantial contribution of aviation to this country.”
A Scottish Government spokesperson said: “Whilst we continue to see growth in overall passenger numbers, continued uncertainty around Brexit and unfavourable exchange rates are having a negative impact on route development in Scotland and elsewhere, as evidenced by Norwegian’s withdrawal of its new routes out of Shannon and Cork where APD does not apply.
"We will continue to work in partnership with Norwegian Air and other airlines, and to support all Scottish airports, to do everything possible to grow the number of international routes to and from Scotland, such as the newly-announced route from Edinburgh to Beijing.
“We are committed to reducing [the replacement] air departure tax by 50 per cent by the end of this Parliament, however we have deferred this until the issues raised in relation to the Highlands and Islands exemption have been resolved to ensure devolved powers are not compromised.”