New figures from US Customs and Border Protection (CBP), indicate that 2.15 million migrants were detained at the US/Mexico border over the past year, a 24% increase, but with a drastic change in the origin of the new migrants, since the fastest growing number are from Venezuela, Cuba and Nicaragua.
On the other hand statistics show that the number of 'traditional' migrants from Mexico and Central America's Northern Triangle of El Salvador, Guatemala and Honduras have fallen dramatically.
In a statement, CBP Commissioner Chris Magnus said that failing Communist regimes were driving a new wave of migration at the border.
Experts point to several other reasons for the spike, including large numbers of repeat crossings and lingering pandemic-related economic issues across the continent.
The rising number of migrants at the border is a politically contentious issue ahead of the US midterm elections in November.
President Joe Biden and other Democrats have been criticized by political opponents over the rise, while there has also been growing tension between the White House and some state governments - most visibly in the form of migrants being bused or flown to Democratic-run areas such as New York and Washington DC.
The number of migrants arriving at the border rose dramatically after Mr Biden took office in late January 2021.
Experts point to a number of reasons for the increase, including environmental disasters, economic woes and political repression.
There's a level of desperation we hadn't quite seen before, said Adam Isacson, a migration and border expert from the Washington Office on Latin America. And you've got people coming from countries that had not sent migrants in significant numbers before now becoming top senders of migrants, due largely to a lack of economic opportunities. Smugglers take advantage of that.
Many of the migrants are now seeking asylum, a process which was severely restricted by the previous US administration of Donald Trump.
Migrants from Mexico and the countries of Central America's Northern Triangle - Guatemala, El Salvador and Honduras - continue to account for the bulk of the total, with Mexicans alone accounting for about 744,000 of the detentions over the past year.
CBP's August figures, however, highlight shifting migration patterns. The number of Mexicans, Salvadorans, Guatemalans and Hondurans fell 43% compared to August 2021. The numbers of Cubans, Nicaraguans and Venezuelans, on the other hand, have risen 175% over the same time period.
Collectively, these three nationalities account for about 494,000 of the migrant detentions this year.
Cuba, for example, has lost much of the aid it received from Venezuela pre-pandemic - creating more economic difficulties there - while Nicaragua's decision last year to eliminate visa requirements for Cubans means they now have a starting point to begin their journey from Central America to the US. A lack of diplomatic relations between the US and these countries also means that the US cannot repatriate them home.