Per its Global Destination Cities Index: Origins report released yesterday 22 July 2019, Mastercard finds that the USA and Mainland China were #1 and #2 global source markets in terms of overnight international visits.
Top destination cities for Americans were:
And for travelers from China:
In the past 10 years, outbound travel from China has risen in rank from #7 to #2, and emerging source markets Republic of Korea and Taiwan (#6 and #10 in 2018, respectively) have joined the Top 10.
And you can follow this link for a free download of the top 3 destination cities and destination countries for each of the Top 10 source markets.