How many flights does a large-scale airline like United or American fly in a single day?

It can vary by season, but last time I looked, United was operating around 1700 flights per day.

United, including its regional partners, operates over 3200 flights a day to over 200 destinations. American, which is slightly larger, will operate over 3300 flights a day.

This info was obtained from the airlines' websites.

Regards,
Dan