Depends on which website you wish to believe. Mandarin chinese places first, english and castilian spanish are both claiming to be second, whereas one is second the other third according to some sites. Clear as mud, isn't it? Personally it doesn't matter.
Well, Spanish is spoken in Spain, all of Central and South America, (including Brazil even though Portuguese is the first language) much of the Southwestern US, several Caribbean islands, several Pacific islands and everywhere Spanish speaking people have gone to live. There's plenty of Spanish spoken in Manhattan, Brooklyn, Queens, Jersey City. I live in Toronto, Canada, and this building's maintenance manager and his wife are Mexican.