The Grammaticalization of "Because" in Standard English
This diachronic investigation of because has its genesis in recent usage developments which deserve scrutiny. Leading up to its naming as the American Dialect Society’s 2013 “Word of the Year,” it was popularly considered, recently by McCulloch (2014) as a subordinating conjunction; alternately it is given as a subordinating preposition (Lobeck and Denham, 2013). Corpora study shows grammaticalization at all levels of linguistic analysis, and show unidirectionality in its clines. Compelling evidence of grammaticalization is detailed in morphophonological, semantic-pragmatic, and syntactic domains.
Guptil, Jeffrey, "The Grammaticalization of "Because" in Standard English" (2017). Western Libraries Undergraduate Research Award. 12.