NFL Blackout / Broadcast Policy Text - NFLMedia.com

This is the official NFL policy on blackouts from NFLMedia.com

BROADCASTING POLICIES

Glossary of Terms
Franchised Market - television market (ADI or DMA) that has an NFL franchise (i.e. Buffalo, NY or Phoenix, AZ).
Secondary Blackout Market - television market in the home territory (with station(s) having signal penetration to within 75 miles of the game site) of an NFL franchise that is subject to blackout restrictions.
Early Game - Game with kickoff at 1:05 p.m. (Eastern Time).
Late Game - Game with kickoff at 4:05 or 4:15 p.m. (Eastern Time).

Blackout Policy
To ensure an NFL club's ability to sell all of its game tickets, and to make televised games more attractive to viewers through the presence of sellout crowds, the following policy is observed by the NFL:

For a home game to be aired locally in the franchised market and in any secondary blackout market(s), the game must be sold out 72 hours in advance of kickoff. If the game is not a sellout by the 72 hour cutoff, both the home franchised market and the secondary markets of the carrying network will air an alternate game.

Number of Games in a Market
With regard to the number of NFL games seen in a particular market on a Sunday afternoon, there are three different situations.
An NFL franchised market (i.e. New York, Chicago, Dallas, etc.).
On a week when the NFL team (or teams) in a market is on the ROAD Sunday, Monday or Thursday night or Saturday afternoon, the market will receive three Sunday afternoon games... two telecasts by the network with the doubleheader week and one game by the network with the single game week. When an NFL team in the market is playing at HOME on Sunday afternoon, the market will receive two games... one game on FOX and one game on CBS, regardless of which network has the doubleheader week. Unless 1) the home team's assigned telecaster that day (CBS or FOX) is also on the doubleheader network and 2) the game is sold out 72 hours in advance. Then the three games would be the home team's and two other games in the remaining early or late window.
All other television markets (including secondary blackout markets).
Network affiliates in these markets will receive three games on Sunday afternoon, two on the doubleheader network (one early and one late) and one game on the single game network (either early or late).
Selection of Games to be Telecast Regionally
By network contract, all team road games must be telecast back to that team's home territory (franchised market and secondary blackout markets).

Other than the above requirement, the televising network is the sole selector of which game(s) will be aired in all markets.