Morning anchor Mike Moss, left, talks to Jim Farley inside the WTOP newsroom in May 2011. (Astrid Riecken/The Washington Post)

Jim Farley, the radio newsman who helped turn WTOP-FM into one of the nation’s most popular and most prosperous stations, said Wednesday he would retire at the end of the year.

Farley, 64, has headed all-news WTOP’s newsroom since 1996 and helped shape and refine its metronomic news-traffic-weather format. Under his direction, the station (heard principally at 103.5 FM in the Washington area) became a juggernaut, with listeners tuning in to its short news reports and “traffic and weather together on the eights” at 10-minute intervals.

Farley said he would continue after his retirement as a consultant to Hubbard Broadcasting, the station’s owner. Hubbard has no mandatory retirement age, but Farley said: “I’ve been going nonstop in the news business since 1966. My wife said, ‘It’s time for you to slow down’ and I agreed with her.” He said he planned to spend more time in Florida and with his four grandchildren in New York and Severna Park.

Under Farley, WTOP’s newsroom more than doubled in size, to 112 journalists, and expanded into digital broadcasting. The station also spun off two new local stations, federal news WFED (1500 AM) in 2002 and news-talk Washington Post Radio (also known as WTWP AM-FM) in 2006 in a joint venture with The Post. The latter proved unsuccessful and ceased broadcasting in 2007. WFED remains on the air.

Farley said his successor is Laurie Cantillo, who was hired as WTOP’s program director in late 2011.

WTOP, which is traditionally among the top-rated stations in the area, has had the highest advertising revenue of any radio station in the nation for the past two years, according to rankings by BIA/Kelsey. Its estimated revenue in 2011, the most recent figure available, was $64 million, the research firm said.