Hi 'Sylvia',
The last twitchable Rose-breasted Grosbeak here was back around the late 80's, the only record of Nighthawk to date was available for one evening only (I couldn't get a lift in time), I managed to see our only Baltimore Oriole (only about 20 birders saw this, including some from the UK), I have NEVER seen an American thrush (didn't get a lift for the Hermit and missed it by an hour or so, was on Cape when the last Swainson's was on the mainland), the last BB Pipit was in the 60's(!!), NOBODY here has YB Cuckoo (never been an available bird, even way back when we got loads of Yanks), managed White-crowned Sparrow two years ago, dipped Bobolink by 5 minutes or less (thanks for reminding me!) and have seen 2 REV's (incl.one self-found bird), also only 2 species of wood warbler (Yellowthroat and Blue-winged Warbler).
I COULD counter with having seen 26 species of true warbler out of 35 on the Irish list, but many birders will have seen more than this in the UK, where Irish megas such as Great Reed Warbler are annual, and there have been twitchable examples of species not yet on the Irish list (Spectacled, Marmora's, Eastern Bonelli's, Lancy etc etc), so what's the point.
Twitching, eh? A load of b***ocks, isn't it...?

Regards,
Harry