Boah, I don&#x27;t even know how long hash tables are in Lisp now. Hash tables became popular when the implementations used them for their symbol tables.<p>The MIT Lisp Machine from the late 70s implemented hash tables and used them widely:<p><a href="http:&#x2F;&#x2F;lispm.de&#x2F;source&#x2F;lispm-system-78-48&#x2F;lispm2&#x2F;hash.lisp" rel="nofollow">http:&#x2F;&#x2F;lispm.de&#x2F;source&#x2F;lispm-system-78-48&#x2F;lispm2&#x2F;hash.lisp</a>