New York players active leaders in career Home Runs.

Two New York Yankees held the season Home Run (HR) record from 1920 through 1997:
Babe Ruth 1920 54, breaking his Red Sox record of 29 in 1919
Babe Ruth 1921 59
Babe Ruth 1927 60
Roger Maris 1961 61

In 1998 Mark McGwire broke that record with 70 HR. Largely unnoticed was that McGwire also became the ACTIVE career HR leader in 1998 because Eddie Murray retired after 1997. Murray had been the active leader in 1990 with Dwight Evans and then alone 1995-1997. McGwire was the active leader 1998-2001, his final season; succeeded by Barry Bonds.

In 1921 Ruth hit career HR number 139, passing Roger Connor, who played for the Giants in the 1800s, for the all time career record and obviously the active leader. Ruth remained the active career HR leader through 1935, his final season, which was with the Boston Braves. So Ruth was a New York player and active career HR leader 1921-1934.

Ruth was immediately succeeded as career leader by former Yankee teammate Lou Gehrig: 1936-1939. Gehrig's career was tragically cut short by in early 1939 due to his physical inability to play.

The only non-Yankee New York player to be career active HR leader since 1921 was New York Giant Mel Ott 1946-1947; Ott then retired with 511, the NL record for many years. Here are the rest of the New York active career HR leaders, all Yankees, after Ott.

Joe DiMaggio 1948-1951; retired with 361

Johnny Mize 1952-1953; retired with 359; succeeded by Red Sox Ted Williams who reached 366 HR in 1954

Mickey Mantle 1964 454; succeeded by former New York Giant Willie Mays who reached 505 in 1965

Alex Rodriguez 2011-2016; succeeded Ken Griffey, Jr. who retired May 31, 2010 with 630 HR; Rodriguez finished 2011 with 629 and retired in August 2016 with 696; since Rodriguez could come out of retirement in 2017 he is still the active leader, I guess, until the 2017 season is complete.

Two prominent Yankees were the career active HR leader after they left the Yankees:

Reggie Jackson 1983-1987 when he retired with 563; Yankee 1977-1981

Dave Winfield 1991-1994; passed by Murray in 1995, Winfield's final season; Winfield finished with 465 HR; Yankee 1981-1990.

Source: http://www.baseball-reference.com/leaders/HR_progress.shtml