AmE Diphthongs
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AmE has only 3 true diphthongs, i.e. vowels with true offglides. They are closing.
There are two reasons for the relatively small number of diphthongs in American English as compared to British English: the absence of centering diphthongs due to the high degree of rhoticity in AE (e.g. in words like here or there) and the classification of monophthongs as long vowels with offglides (e.g. / w / in / ow / ).
(Click on the symbols in the chart to retrieve an audio example and a glide animation.)