The OpenClipArt site has been down for 21 days now, apparently felled by a heavy denial-of-service (DDOS) attack. It has 150,000 bits of clipart, all under CC Zero. Archive.org has a partial mirror of the site, but it’s no use for keyword searching or (it seems) getting the actual image files.
While Wikimedia Commons holds 2,000 images tagged with ‘OpenClipArt’, they didn’t ingest all 150,000 bits of the OpenClipArt clipart. In fact, no-one seems to have done so, and there are also no recent tar.gz archives containing all 150,000 items. The 0.18 and 0.19 releases were 2010 and 2011, and while a 310Mb author-sorted 2.0 release followed, there doesn’t appear to have been a more recent 3.0 release of the archive.
Thus it seems to me that the site Public Domain Files by Open Clip Art Library is the best fallback until OpenClipArt is back up again. It has a searchable partial mirror of 13,778 OpenClipArt images files, with the latest of these dated to mid summer 2014, and the site has no Shutterstock-ery, pop-ups or ‘mailing-list blocking overlay’ nastiness that I could see (while running an ad-blocker).
Once OpenClipArt is back online it would probably be a good idea to archive and distribute a big compressed mirror of the summer 2019 contents, if only in .SVG format.