Official figures show there were more than 707,000 visits from North America in the year to the end of June, up 38 per cent on the previous 12-months.
Visitors from North America also spent more, with figures showing a 48 per cent rise over the period, from £495 million to £732 million.
Across all international markets visits to Scotland were up 11 per cent and spending increased by 19 per cent to more than £2 billion.
Tourism Secretary Fiona Hyslop said: “The continued rise in overseas tourists is encouraging. They are spending more too, particularly those coming from North America.
“It is great news for our economy. Scotland offers an memorable visitor experience for people that choose our country as their holiday destination.”
Historic Environment Scotland said that sites which feature in the hit US television series Outlander, based on the books by Diana Gabaldon, saw a large increases in visitor numbers. Blackness Castle saw the most significant rise in visitors at 44 per cent, closely followed by Doune Castle – famed for its role as the fictional Castle Leoch in the series – with a 42 per cent increase.