Proposed in 1908 as part of the new Latvian spelling by the scientific commission headed by K. Mīlenbahs, which was accepted and began to be taught in schools in 1909. Prior to that, Latvian had been written in German Fraktur, and sporadically in Cyrillic.
Despite being an independent letter with its own position in the Latvian alphabet, Ē/ē, like all long vowels with macrons, is treated as a simple E/e in alphabetized lists (e.g., in dictionaries).
The letter Ē/ē (like its short counterpart E/e) represent two sounds, [ɛ] — šaurais e (“narrow e”) — and [æ] — platais e (“broad e”). In principle, [ɛ] is used when there is a palatal element (the vowels i, ī, e, ē, the diphthongs ie, ei, and the palatal consonants j, ķ, ģ, ļ, ņ, š, ž, č, dž, and, in the old spelling, ŗ) either in the same or in the following syllable; otherwise, [æ] is used. Unfortunately, some historical changes have obscured this pattern by removing some previously existing palatal elements; as a result of that, for a number of words the actual pronunciation of the letter e — [ɛ] or [æ] — must be memorized.