More than likely WACA ("Radio America novecientos AM") in Laurel MD. WJWL in Georgetown DE is also Spanish ("La Raza", but WACA is more commonly heard here.
I had 'America' WACA while driving down the 404/DVP just after sunset on Thursday. But 'Raza' WJWL seems more common at night. Mexico also has been in at night. One 900 station I'm hoping for is Barbados. Nary a trace thus far.