Harry Vardon wins the U.S. Open, the first golfer to win both the British and U.S. Opens.
(1900)

Golf is placed on the Olympic calendar for the 2nd Games at Paris.
(1900)

Walter Travis becomes the first golfer, in the U.S. Amateur, to win a major title with the Haskell ball. When Sandy Herd wins the British Open and Laurie Auchterlonie the U.S. Open the next year with the Haskell, virtually all competitors switch to the new ball.
(1901)

Sunningdale, a course built amidst a cleared forest, opens for play. It is the first course with grass grown completely from seed. Previously, golf courses were routed through meadows, which frequently created drainage problems as the meadows were typically atop clay soil.
(1901)

The first course at the Carolina Hotel (later the Pinehurst Resort & CC) in Pinehurst, N.C., is completed by Donald Ross. Ross will go on to design 600 courses in his storied career as a golf course architect.
(1901)

England and Scotland inaugurate an Amateur Team competition, with Scotland winning at Hoylake.
(1902)

The first grooved-faced irons are invented.
(1902)

Oakmont C.C. is founded in Oakmont, Pennsylvania, designed by Henry Fownes. It is widely regarded as one of the finest examples of penal-style golf architecture.
(1903)

Walter J. Travis becomes the first American to win the British Amateur.
(1904)

Women golfers from Great Britain and the United States play an international match, with the British winning 6 matches to 1.
(1905)

The first dimple-pattern for golf balls is patented by William Taylor in England.
(1905)

The Complete Golfer by Harry Vardon is published. It promotes and demonstrates the Vardon or overlapping grip.
(1905)

Goodrich introduces a golf ball with a rubber core filled with compressed air. The "Pneu-matic" proves quite lively, but also prone to explode in warm weather, often in a golfer's pocket. The ball is eventually discontinued; at this time the Haskell ball achieves a dominance of the golf ball market.
(1906)

Arnaud Massey becomes the first golfer from the Continent to win the British Open.
(1907)

Mrs. Gordon Robertson, at Princes Ladies GC, becomes the first female professional.
(1908)

The Mystery of Golf by Arnold Haultain is published.
(1908)

The USGA rules that caddies, caddymasters and greenkeepers over the age of sixteen are professional golfers. The ruling is later modified and eventually reversed in 1963.
(1909)

The R&A bans the center-shafted putter while the USGA keeps it legal-marking the beginning of a 42-year period with two official versions of The Rules of Golf.
(1910)

Steel shafts are patented by Arthur F. Knight.
(1910)

J.J. McDermott becomes the first native-born American to win the U.S. Open. At 17 years of age, he is also the youngest winner to date.
(1911)

John Ball wins his eighth British Amateur championship, a record not yet equalled.
(1912)

Francis Ouimet, age 20, becomes the first amateur to win the U.S. Open, defeating favorites Harry Vardon and Ted Ray in a play-off.
(1913)

The first professional international match is played between France and the United States at La Boulie, France.
(1913)

Formation of The Tokyo Club at Komozawa kicks off the Japanese golf boom.
(1914)

Harry Vardon wins his sixth British Open, a record to this day (Peter Thomson and Tom Watson have since won five Opens each).
(1914)

The British Open is discontinued for the duration of the First World War.
(1915)

The PGA of America is founded by 82 charter members and the PGA Championship is inaugurated. James Barnes is the first champion.
(1916)

The first miniature golf course opens in Pinehurst, North Carolina.
(1916)

Francis Ouimet is banned from amateur play for his involvement with a sporting goods business. The ruling creates a stir of protest and is reversed in 1918.
(1916)

The PGA Championship and the U.S. Open are discontinued for the duration of the First World War.
(1917)

The R&A assumes control over the British Open and the British Amateur.
(1919)

Pebble Beach Golf Links opens as the Del Monte G.L. in Pebble Beach, California.
(1919)

The USGA founds its famed Green Section to conduct research on turfgrass.
(1920)

The first practice range is opened in Pinehurst, North Carolina.
(1920)

The Professional Golfer of America is first published which, today known as PGA Magazine, is the oldest continually-published golf magazine in the United States.
(1920)

The R&A limits the size and weight of the ball.
(1921)

Walter Hagen becomes the first native American to win the British Open. He subsequently becomes the first professional golfer to open a golf equipment company under his own name.
(1922)

The Walker Cup Matches are instituted. The grandson of Walker Cup founder George Herbert Walker is George H.W. Bush, the 41st President of the United States.
(1922)

The Prince of Wales is elected Captain of the R&A.
(1922)

The Texas Open is inaugurated, the second-oldest surviving PGA TOUR event.
(1922)

Pine Valley Golf Club opens.
(1922)

The West and East courses at Winged Foot Golf Club open for play, designed by A.W. Tillinghast.
(1923)

Joyce Wethered wins her record fifth consecutive English Ladies' Championship.
(1924)

The Olympic Club in San Francisco opens for play.
(1924)

The USGA legalizes steel shafted golf clubs. The R&A does not follow suit until 1929, widening the breach in The Rules of Golf.
(1924)

The first fairway irrigation system is developed in Dallas, Texas.
(1925)

Deep-grooved irons are banned by both the USGA and the R&A.
(1925)