NEW YORK — The CBS drama "Under the Dome" has the potential to be a game-changer for network television.

An estimated 13.5 million people watched the debut a week ago Monday of the summer series based on a Stephen King book about an invisible dome landing over a small town, the Nielsen company said. It's been 20 years since a new summertime drama opened so strongly.

An additional 3.2 million people watched "Under the Dome" either on their DVRs or by ordering it through an on-demand service, Nielsen said. CBS reran the premiere Sunday night, and 5.1 million people watched.

Numbers that big surely compel a response in television executive suites. Even before "Under the Dome," Fox had talked about creating big event dramas with a limited run, including a return of "24." Broadcast networks have wondered for years how to stem erosion during the summer, and a successful drama came along at just about the time the reality franchises they had been relying on were beginning to age.

The second episode of "Under the Dome" that aired this Monday was seen by 11.5 million viewers.

CBS said it will air 13 episodes before it ends in September. Its executives have talked about continuing the series beyond that, most likely next summer.

CBS won the week in prime time, averaging 5.7 million viewers. NBC had 4.9 million viewers, ABC had 3.7 million, Univision had 3.6 million, Fox had 3.3 million, Telemundo had 1.8 million, ION Television had 1.3 million and the CW had 710,000.

USA was the week's most popular cable network, averaging 2.7 million viewers in prime time. TNT had 2.4 million, The Disney Channel had 2.3 million, History had 2.13 million and TBS had 2.05 million.

NBC's "Nightly News" topped the evening newscasts with an average of 7.5 million viewers. ABC's "World News" was second with 6.7 million and the "CBS Evening News" had 6.1 million viewers.

For the week of June 24-30, the top 10 shows, their networks and viewerships: "Under the Dome," CBS, 13.53 million; "America's Got Talent" (Tuesday), NBC, 10.23 million; "NCIS," CBS, 8.37 million; NHL Stanley Cup Final, Game 6: Chicago vs. Boston, NBC, 8.16 million; "The Big Bang Theory" (Thursday, 8 p.m.), CBS, 8.15 million; "The Big Bang Theory" (Monday, 9:30 p.m.), CBS, 7.35 million; "60 Minutes," CBS, 7.17 million; "The Big Bang Theory" (Monday, 9 p.m.), CBS, 6.65 million; "The Bachelorette," ABC, 6.56 million; "Big Brother 15" (Wednesday), CBS, 6.51 million.