What is the etymology for "the straight dope"?

[samclem]

I posted this back in 2008 when it was asked previously.

@samclem

The OED is still one of the most respected reference sources in the world, as it well should be. Something that mammoth doesn’t update itself overnight. The OED is currently updating around the letter “R” if I’m not mistaken. Most entries that haven’t been updated are from before 1989. That precludes the wonderful world of digital electronic newspaper databases, et al.

The earliest found cite for “straight dope” meaning the correct information is 11 May 1904 by me. It was in the Anaconda(MT) Standard.
Quote:
The citizens would gladly send her a basket of flowers if she should give out the straight “dope” regarding the whereabouts of the assassin of Cronin.

Note that “dope” is in quote marks, indicating that it was a rather new word.

The modifier “straight” was added about this time to the previously used word “dope” which meant information, first appearing in the late 1890s referring to horse racing information, usually inside information. Other uses of “dope” in relation to horse racing at this time included dope sheets, dope book, dope out. In all cases, it referred to information about things, usually horse racing.

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