This study uses data from the Corpus of Spoken Yiddish in Europe to compare the acoustic correlates of the length contrast in the peripheral vowels of two regions within the Central Yiddish dialect area: central Poland, considered the more conservative variety, and the Transcarpathian Unterland, hypothesized to have diverged from Polish Yiddish in the prewar period. Findings reveal smaller duration differences in [iː] versus [i] and [aː] versus [a] among Unterland speakers compared to speakers from Poland, with a gender effect in the Unterland showing smaller duration distinctions among women. The duration difference in [uː] versus [u] is significantly smaller than the other vowel pairs in both regions, likely reflecting its ambiguous phonemic status. Vowel quality shows no systematic differences between the two regions. The findings point to the possible influence of population mobility, dialect mixing, geopolitics, and multilingualism on vowel systems.