I wouldn't say there is 50 of them but there are more pigs than Blades in New York. We'd occasionally run into them if both teams played on the same day, as both sets of fans would watch the games in Football Factory - before that it was Nevada's on 3rd Avenue. Kevin McCabe once showed up for a Blades match there.
I only knew four Blades who actually lived in NYC when I did, but numbers were often swelled by Blades on holiday. One time there were at least 20 of us in Football Factory for a derby match, and a few more pigs.
I left about 5 years ago, and by then watching football in bars had become less popular because you could get a stream for every match, and the kick-off times were usually 10am or earlier.
The numbers may have been swollen by friends and people on holiday, but there are at least 50 members of the supporters club.
The manager put on a breakfast buffet on as it was a 12.15pm kick off, 7.15am in New York.