Boundary-related lengthening has been shown to affect the phrase-final word in a number of languages, but its precise distribution within the final word has not been determined. Some evidence suggests that it can begin before the final syllable (e.g. in an earlier main-stress syllable), and that it may be progressive (e.g. may affect the coda of the final syllable more than the nucleus and the nucleus more than the onset). However, only a small number of word shapes have been examined in any one language, so the available facts under-determine models of the duration adjustment process. A survey of final lengthening in words with various stress patterns in American English, using acoustic measures, shows that, in the conditions of these experiments, (a) although most of the duration increase occurs in the phrase-final syllable rime, statistically significant lengthening of 7-18% also occurs in the main-stress syllable rime, when the main stress syllable is not the final syllable, (b) this pattern is seen in both pitch-accented and unaccented final words, suggesting that it is not the result of nuclear-accent-related lengthening, (c) the distribution of lengthening across the syllables of the final word is not straightforward, in the sense that regions between the main-stress rime and the final rime appear to be skipped or lengthened less than the regions before and after them. These results suggest that the mechanism of boundary-related lengthening is more complex than current models propose; in particular, its distribution cannot be explained without reference to the location of main lexical stress and appears to involve more than one stretch of speech, at least in American English. (C) 2007 Elsevier Ltd. All rights reserved.