May 8, 1877: New York goes to the dogs
In terms of American sporting events, only the Kentucky Derby is older – and by just two years. On this day in 1877, the Westminster Kennel Club held its first dog show.

The format has changed a bit since 1877. Originally, it was a festival for gun dogs, founded by a group of hunters who hung out at the Westminster Hotel near Union Square. It took place at what would become the first Madison Square Garden; the WKC today holds its show at the fourth MSG incarnation.
In 2015, 177 breeds competed in seven groups: Herding, Hound, Non-sporting, Sporting, Terrier, Toy, and Working. In addition, there are 15 breeds in the Miscellaneous Class, under consideration for future inclusion as an official breed.
Best in Show was first given out in 1907. Warren Remedy, a Smooth Fox Terrier, won that year – as well as the next two. He remains the only dog to win three times; five dogs have won twice, but nowadays, most winners end up retiring.
As a group, Terriers have won 46 of 108 Best in Shows, with the Wire Fox Terrier responsible for 14 of those. The most recent champion is a Hound, a 15-Inch Beagle named Miss P.
For more on the Westminster Kennel Club Dog Show, check out the WKC’s official history.
Here are a few pictures from 2011, when my mom and I went:

Bullmastiffs competing for best of breed

A Samoyed in the benching area, about to be groomed

The floor during the breed judging; these preliminary competitions are now held elsewhere

I see your 1877 and raise you to 1851. The America’s Cup is the oldest contested trophy in sport. And, if you want to get picky, the first defense of the cup that took place on US soil was in 1870, still before 1877. Now the “America” in the title refers to a boat. Still the America’s Cup event took place in the US on an irregular schedule continuously up to 1983 when the Australia II took the cup to Freemantle Australia. The cup has come and gone from the US a couple of times since. Technically it is currently in American hands, specifically those of Oracle’s Larry Ellison. Ellison successfully defended the Cup (just barely) in 2013 in San Francisco. In spite of this, or perhaps because of this, the next defense is scheduled for June of 2017 in Bermuda. For most if its life the Cup has had a New York home, residing in the primary clubhouse of the New York Yacht Club on West 44th St.
Good history. But neither continuously on US soil nor annual 😉
Neither of those criteria is mentioned in the blurb above. However, I am guessing you have never personally attended an America’s Cup race. For a full up Cup defense, your last chance to attend one reasonably close by would have been the 1983 event in Newport RI a mere 30 odd years ago. So I can understand a bias in favor of an event you have personally attended.
The ’83 Cup was the first one to be shown on TV. Initially it was only shown locally in RI. But as the suspense built (the US jumped to a big early lead but the Ausies clawed their way back to tie the whole thing at three wins each) national interest built. There was time for this to happen because only one race is run in a day and frequent “lay days” are thrown in. So the final race was televised nationally in both the US and Australia. Needless to say the Ausies were much happier with the final result than the Americans were.
Do you know what year Westminster started live TV coverage?