Transported mineral dust in a Saharan air layer (SAL) contains highly active ice-nucleating particles (INPs) that may be transported across the Atlantic Ocean and subsequently seed clouds in the Caribbean and the Americas. During an aircraft campaign around Houston and the western U.S. Gulf Coast, a widespread SAL advected into the sampling region allowing for measurement of the ice-nucleating ability of SD following long-range transport. Results showed that the mean INP concentrations were 3–4.5 times higher than non-Saharan dust (nSD), but only at temperatures < –21 ºC. Active surface site densities were also enhanced in the SD, exceeding the mean for nSD by over an order of magnitude at temperatures < –21 ºC. These INP measurements confirmed that SD remains a highly active INP even after > 8000 km westward transport across the Atlantic Ocean.