Yom HaAtzma’ut commemorates the declaration of independence of Israel in 1948. Note that Hebcal displays modern holidays like Yom HaAtzma’ut according to the Israeli schedule. Although Yom HaAtzma’ut is normally observed on the 5th of Iyyar, it may be moved earlier or postponed if observance of the holiday (or Yom HaZikaron, which always preceeds it) would conflict with Shabbat.
List of Dates
Yom HaAtzma’ut begins at sundown in the Diaspora on:
References: The Jewish Holidays: A Guide & Commentary
Rabbi Michael Strassfeld
Tanakh: The Holy Scriptures Jewish Publication Society