VLBI (very long baseline interferometry) measurements have been made during the 1990s at sites in the Caribbean (St. Croix, US Virgin Islands) and South America (Fortaleza, Brazil and Santiago, Chile) and the site velocities are now well determined. In the NUVEL-1A NNR frame, the VLBI velocity of St. Croix of 19.0¿0.7 mm/yr at N72.3¿2.0 ¿E with respect to North America is significantly larger than the corresponding NUVEL-1A relative velocity of 11.4 mm/yr at N80 ¿E. Fortaleza is in the stable portion of the South American plate in northeastern Brazil and its speed relative to the NUVEL-1A NNR South American plate velocity is only 1.2¿0.7 mm/yr. Santiago has a horizontal velocity of 21.2¿0.8 mm/yr at N70.7¿2.2 ¿E with respect to the NUVEL-1A NNR South American plate velocity and a vertical rate of 5.2¿1.7 mm/yr. The strike-perpendicular horizontal component and the vertical component of this velocity are consistent with a simple elastic dislocation model of a locked South America-Nazca plate interface near Santiago. ¿ 1999 American Geophysical Union