According with Squaremouth, a travel insurance site comparison, there are five international destinations seeing a huge boost from American travellers, since last year:

• Israel: +50%
• Iceland: +43%
• Porugal: +42%
• Vietnam: 39%
• Norway: 36%

While the stats only apply to US travellers who purchased insurance with Squaremouth, last year the World Tourism Organization released its list of the fastest-growing tourist destinations globally, being Portugal the first among Southern and Mediterranean Europe countries with more than 10million international arrivals:

• Portugal: +12,7%, 11,4 million arrivals
• Spain: +10,3%, 75,6 million arrivals
• Croatia: +8,9%, 13,8 million arrivals

Please read the full UNWTO report here.

Finally, according with the European Cities Marketing, Lisbon ranks #15 in the top 15 of european cities by bednights in 2016 . with 9,7 million bednights, being the 3rd fastest growing destination after Barcelona and Amsterdam.

Hope this information is valuable for you, in the perspective of a real estate investor.