The *most* Republican district on there was a gerrymander to protect Brooklyn's last Republican assembly member IIRC.
Fell in 2006, IIRC. In which case the 2008 result is, well, wow.
I think you must have another district in mind - Dov Hikind has been assemblyman for District 48 since the 80's. As to why such a Republican district shows up on the map as so Dem, the crazy New York ballot system strikes again:
Dov Hikind REP 10,521
Dov Hikind DEM 8,397
Herbert F. Ryan CON 1,139
Party affiliation notwithstanding, Hikind endorsed McCain (and Bush). He is basically a Kahanist. (As in, actually - I'm not using this as a generic slur against right-wing Zionists).
Possibly.
Sad to say, but it's more likely is that I did only some quite insufficient research and jumped to conclusions somewhere... maybe a list with Dem and Rep by AD votes that, like, didn't point out that they were for the same guy, and where he had more R votes in 04 but more D votes in 06. Or something along those lines. Together with the district's bizarro borders.