had skip-stop service
... that the Dearborn Street Subway had skip-stop service in 1951 for one morning before it was discontinued?
... that the <a href="./Milwaukee–Dearborn_subway" id="mwA7k" rel="mw:WikiLink" title="Milwaukee–Dearborn subway">Dearborn Street Subway</a> <b id="mwA7o"><a href='./Skip-stop_on_the_Chicago_"L"' id="mwA7s" rel="mw:WikiLink" title='Skip-stop on the Chicago "L"'>had skip-stop service</a></b> in 1951 for one morning before it was discontinued?