The link to Breezewood, Pennsylvania, was especially fun because it has a link to a list of freeway gaps in the Interstate Highway system. It turns out that I've been on two of four actual interrupted freeways, four out of six at grade sections, and three out of eight drawbridges.
I used to go through Breezewood on my way east to Baltimore and DC, but now I jump off 70 in Washington, PA go south to Morgantown, West (by God) Virginia and pick interstate 68 across Maryland. Got tired of paying tolls in PA.
Been to 5 on the US list - thanks for the link.