grammar

All my writing life I've had rather tedious arguments with purists over one of the unresolved arguments in english grammar. Which is correct: "The Penn Pike is installing signs…" (collective singular, CS) or "The Penn Pike are installing new signs" (collective plural, CP).

All my life I've run into passionate adherents of both. My mother of English/Scots upbringing was a CPer, but my father of German birth and education was a CSer. It was a family argument, and I decided very early in life that both were right.