US Code Title 17, Chapter 1, § 110. LIMITATIONS ON EXCLUSIVE RIGHTS: EXEMPTION OF CERTAIN PERFORMANCES AND DISPLAYS
(4) performance of a nondramatic literary or musical work otherwise
than in a transmission to the public, without any purpose of direct or
indirect commercial advantage and without payment of any fee or other
compensation for the performance to any of its performers, promoters,
or organizers, if—
[...lots of other rules...]
if the performance or display is by audiovisual means, any visual
portion of the performance or display is communicated by means of a
total of not more than 4 audiovisual devices, of which not more than 1
audiovisual device is located in any 1 room, and no such audiovisual
device has a diagonal screen size greater than 55 inches, and any
audio portion of the performance or display is communicated by means
of a total of not more than 6 loudspeakers, of which not more than 4
loudspeakers are located in any 1 room or adjoining outdoor space;
However, private viewing in private house is exempt from these rules, so at home you can have as big TV as you'd like. This includes having a private Super Bowl party at home.
Read more in ArsTechnica: "Will your big-screen Super Bowl party violate copyright law?"