A Space or Two Spaces?

     This is a topic that we recently debated at my work. Do you type one space or two spaces after a sentence-ending period?

• The Chicago Manual of Style - you will always use only one space after a period. Chicago’s online Q&A section states that “there is no proof that an extra space actually improves readability,” and “CMOS follows the industry standard of one space after a period.”
• MLA Handbook - you will “Leave one space after a period or other concluding punctuation mark, unless your instructor prefers two spaces,” under the text formatting section.
• APA’s Sixth Edition - is returning to the use of two spaces after a period, “Punctuation—return to two spaces after the period at the end of the sentence recommended for ease of reading comprehension.”

     After reading through multiple sites, it appears that most style guides have come to the agreement that only one space is needed after a period. I read various articles and blogs that state the use of the extra space comes from when typewriters were commonly used and is no longer needed since the default spacing on electronic devices is more “readable.” I conclude that we only need to use one space after periods.