The proclamation is linked here.
Update 1: Headline, The New York Times, March 5, 2019:
Border at ‘Breaking Point’ as More than 76,000 Unauthorized Migrants Cross in a Month
Update 2: Reasons President Obama gave in February 2016 for continuing the national emergency on Cuba that was declared by President Clinton in 1996:
Whereas the Cuban economy is in a relatively weak state, contributing to an outflow of its nationals towards the United States and neighboring countries;
Whereas the overarching objective of U.S. policy is stability in the region, and the outflow of Cuban nationals may have a destabilizing effect on the United States and its neighboring countries;
Whereas it is United States policy that a mass migration from Cuba would endanger the security of the United States by posing a disturbance or threatened disturbance of the international relations of the United States…