1942
Austin J. Tobin is appointed executive director of the Port of New York Authority, which later will be renamed the Port Authority of New York and New Jersey.

July 22, 1944
Forty-three nations meet to negotiate the Bretton Woods agreement, an American and British plan establishing a postwar economic order based on the primacy of the U.S. dollar, and intended to encourage the reconstruction of the world's war-shattered economies through the expansion of international trade.

1945
David Scholtz, a real estate developer and former governor of Florida, first proposes a concept for a "world trade center" in Lower Manhattan to encourage port and maritime activities in New York.

1946
The New York State legislature authorizes a World Trade Corporation to develop the proposed World Trade Center and appoints Winthrop Aldrich, chairman of the Chase Bank (and uncle of David and Nelson Rockefeller), to explore the feasibility of the concept.

In December, encouraged by his sons Nelson and David, John D. Rockefeller Jr. donates $8.5 million to the United Nations to purchase a site along the East River for the world organization's permanent headquarters.

1947
David Rockefeller initiates an ambitious urban renewal plan for Morningside Heights in upper Manhattan, the location of Columbia University and other educational and religious institutions.

1948
The U.S. Congress passes the Marshall Plan to aid the economic reconstruction of Western Europe.

New York has become the world's largest center for manufacturing, wholesaling and shipping. It has also become the world's financial and corporate capital.

April 4, 1949
Ten European nations, Canada and the United States sign the North Atlantic Treaty. America's first-ever peacetime military alliance.

Also this year, congress passes Title I urban renewal legislation.

November 1955
David Rockefeller announces a plan to construct the new headquarters for the Chase Manhattan Bank in Lower Manhattan. Built at a cost of $121 million, the 60-story building, known as 1 Chase Manhattan Plaza, is intended to initiate the revival of the downtown financial district.

1956
The Downtown-Lower Manhattan Association is started, spearheaded by David Rockefeller.

1958
John D. Rockefeller III, Nelson and David's brother, initiates the development of the Lincoln Square project, an urban renewal effort to create a performing arts complex, Lincoln Center, on Manhattan's Upper West Side.

October 1958
The Downtown-Lower Manhattan Association (D.L.M.A.) and David Rockefeller release an 80-page master plan for the transformation of Lower Manhattan through traffic improvements and the creation of new housing, office buildings, and recreational facilities, including a new exhibition-and-office complex dedicated to world trade.

Within a few weeks, brother Nelson A. Rockefeller will be elected governor of New York.

January 1960
The D.L.M.A. releases its formal plan for a five million square foot World Trade Center on the East Side of Manhattan, and proposes that the Port Authority of New York and New Jersey "study" the concept's feasibility.

December 1960
Austin Tobin agrees that the Port Authority will begin planning for the World Trade Center project.

Spring 1961
In March, the Port Authority releases its plan for a World Trade Center along the East River, featuring several office buildings and a major exhibition hall for industrial products. New Jersey governor Richard Meyner claims the proposed project will do little for his state.

The New York and New Jersey legislatures approve the joint Port Authority Trans-Hudson/World Trade Center bill. It is quickly signed by Governor Nelson Rockefeller and newly elected New Jersey governor Richard Hughes.

December 1961
Responding to objections from New Jersey, the Port Authority relocates the World Trade Center site from the East River to a 16-acre parcel of land along the Hudson River. The new site is located above the Manhattan terminus of the Hudson & Manhattan Railroad, a deteriorating commuter line which the Port Authority has agreed to take over, renovate, and rename the Port Authority Trans-Hudson line.

1962
Local businessmen in Lower Manhattan, many of them part of an electronics district known as "Radio Row," begin a series of legal and political challenges to the World Trade Center, whose development will eliminate their businesses. Their protests will continue for four years.

February 1962
Port Authority employee Guy Tozzoli takes over the planning and operations of the enormous building project.

September 12, 1962
Encouraged by recent successes in the space program, President John F. Kennedy announces to the nation his intention that the United States land a man on the moon before the end of the decade, marking the start of what becomes the Apollo Project.

October 1962
The Detroit-based architect Minoru Yamasaki is hired as primary designer of the trade center, working in association with Emery Roth & Sons, a New York architecture firm known for its speculative building projects.

January 1964
The completed design of the World Trade Center, consisting of twin 110-story towers along with four smaller structures surrounding a central plaza, is presented at a press conference at the New York Hilton.

Also this year, the New York World's Fair opens in Flushing Meadows, Queens.

March 1966
The New York State Court of Appeals turns back the final legal challenge to the World Trade Center, clearing the way for the project to proceed.

Demolition of existing structures on the site begins on March 21.

August 1968
Steel work begins on the north tower of the World Trade Center. It will begin on the south tower the following January.

April 1970
While construction of the towers continues, scores of construction workers (called "hardhats" in the press) attack demonstrators protesting the Vietnam War in Lower Manhattan.

December 23, 1970
The final column of the north tower is hoisted into place on the 110th floor where the workers hold their traditional "topping-off" ceremony. That same week, the first tenants begin moving into the lower floors of the building.

Spring 1972
After several years of criticism and attacks from New Jersey governor William Cahill, Austin Tobin decides to retire from the Port Authority, ending a 30-year-long tenure as director, and a 45-year career at the agency.

April 4, 1973
The Port Authority holds a dedication ceremony for the World Trade Center in the north tower. Austin Tobin does not attend.

The following month, in May, the 1,454-foot Sears Tower in Chicago opens, and surpasses the World Trade Center as the world's tallest structure by 100 feet.

August 7, 1974
Just after 7am, a French wirewalker named Philippe Petit crosses the 131-foot divide between the tops of the two towers eight times, to the delight — and terror — of thousands of New Yorkers watching from below. Afterwards he is arrested and "sentenced" to perform free highwire acts for children in Central Park.

December 19, 1974
Nelson Rockefeller is sworn in as vice president of the United States. Following Richard Nixon's resignation in August, President Garald Ford had nominated Rockefeller to the position, despite the fact that Rockefeller did not serve as an elected official.

Summer 1975
The observation deck opens on the 110th floor of the south tower, and quickly becomes one of the most popular tourist attractions in the city.

October 1975
New York's fiscal crisis comes to a climax, threatening the city with bankruptcy, and bringing to a culmination years of growing social and economic troubles. In November, the Daily Newssummarizes President Gerald Ford's refusal to provide loan guarantees for New York with the headline: "Ford to City: Drop Dead."

Spring 1976
Reversing his earlier stance, President Ford agrees to guarantee emergency loans for the city, and New York begins its gradual recovery from the financial crisis.

In May, Windows on the World— called "the greatest restaurant in the world" by food critic Gael Greene — opens its doors on the 106th and 107th floors of the north tower.

July 4, 1976
Operation Sail takes place in New York Harbor for the nation's bicentennial. Dozens of "tall ships" parade down the Hudson past the newly completed World Trade Center.

May 27, 1977
George Willig, a 27-year-old toy designer from Queens, scales up the side of the north tower in three hours; the press dubs him "The Human Fly."

1980
A long economic boom begins, centered on Wall Street. It brings a flood of new investment, new construction, and new populations to New York. After years of financial losses for its owners, the World Trade Center begins to turn a profit, and is producing $187 million a year in net income by 1987.

October 20, 1987
On "Black Monday," the long bull market comes to a sudden end when the New York Stock Exchange drops 508 points, the greatest single-day loss in its history.

February 26, 1993
At 12pm, a group of fanatical Muslim fundamentalists detonate a van filled with 4,000 pounds of explosives in an underground parking garage beneath the north tower of the World Trade Center, killing six people and injuring more than a thousand, while failing to structurally damage the towers. Six conspirators will be convicted of the crime and given prison sentences of 240 years apiece.

November 1993
Rudolph Giuliani, a former U.S. Attorney, is elected mayor of New York and vows to decrease crime and restore civic order in the city.

1994
As crime and disorder drop in the city dramatically, a new boom begins to take hold in New York, bringing an upsurge in economic activity and a new influx of immigrants from around the globe. At the World Trade Center, the original port-related tenants and government agencies will be replaced by wealthy financial services companies, leasing multiple floors by 2001.

2000
The U.S. Census Bureau reports that the population of New York City, after dropping for three decades, has increased by more than 700,000 since 1990 to top the eight million mark for the first time in the city's history.

Summer 2001
The World Trade Center buildings -- now among the most profitable parcels of real-estate on earth -- are sold to a private landowner, Larry Silverstein, for over a billion dollars.

September 11, 2001
Terrorist attacks on the United States. Timeline of events (Eastern Daylight Time):

8:46am
American Airlines flight 11, flying from Boston to Los Angeles with 92 people on board, crashes into the north tower of the World Trade Center in New York City, ripping into multiple floors and igniting a massive fire.

8:47am
Firefighters and emergency crews begin heading for the Trade Center.

8:50am
Bridges and tunnels leading to Lower Manhattan are closed to all but emergency vehicles.

9:02am
United Airlines flight 175, flying from Boston to Los Angeles with 65 people on board, crashes into the south tower of the World Trade Center, damaging multiple floors and bursting into flames.

9:17am
The Federal Aviation Administration shuts down every airport in the New York City area.

9:21am
The Port Authority of New York and New Jersey closes every bridge and tunnel in the New York area.

9:30am
From Florida, President George W. Bush announces the country has suffered an "apparent terrorist attack," and pledges that the United States will hunt down the responsible parties.

9:38am
American Airlines flight 77, flying from Dulles Airport in Washington, D.C. to Los Angeles with 64 people on board, crashes into the Pentagon, in northern Virginia, and explodes into flames.

9:40am
The Federal Aviation Administration (F.A.A.) halts all flight operations at American airports, and orders every commercial airliner to land immediately, marking the first time in U.S. history that air traffic nationwide has been suspended.

9:48am
In Washington, D.C., workers are evacuated from the U.S. Capitol and the White House.

9:58am
The south tower of the World Trade Center collapses.

An emergency operator in Pennsylvania receives a call from a passenger on United Airlines flight 93, flying from Newark to San Francisco with 45 people aboard, stating the plane is being hijacked.

10:10am
Damage from the plane crash causes part of the Pentagon to collapse.

United Airlines flight 93 crashes to the ground in Somerset County, Pennsylvania, southeast of Pittsburgh, heroically brought down by its own passengers after hearing about the attacks on the World Trade Center. Officials later speculate that the plane's hijackers had intended to attack the White House or the Capitol.

10:13am
In New York City, the United Nations is evacuated.

10:24am
The F.A.A. diverts all transatlantic aircraft flying to the U.S., sending them to Canada.

10:28am
The north tower of the World Trade Center collapses.

11:02am
New York mayor Rudolph Giuliani orders Lower Manhattan to be evacuated.

11:40am
With the U.S. military on nuclear alert, President Bush is taken to Barksdale Air Force Base in Louisiana.

1:04pm
From Barksdale Air Force Base, President Bush states that the nation is taking appropriate security measures, and the U.S. military is on high alert worldwide. He asks Americans to pray for the victims of the attacks and says America "will hunt down and punish those responsible for these cowardly acts." The President will soon depart for Offutt Air Force Base in Nebraska.

1:44pm
The Pentagon announces that two aircraft carriers, the U.S.S. George Washington and the U.S.S. John F. Kennedy, along with five other war ships, are leaving the U.S. Naval Station in Norfolk, Virginia, headed for New York.

2:49pm
Mayor Giuliani announces that New York's subway and bus service have been partially restored. When asked how many people he thinks have been killed, Giuliani voices the grief many feel by saying, "I don't think we want to speculate about that -- more than any of us can bear."

4:00pm
U.S. officials say there are "good indications" that Saudi terrorist Osama bin Laden, who is suspected of coordinating the bombings of two U.S. embassies in Africa in 1998, is behind the attacks.

4:10pm
Number 7 World Trade Center, which sustained massive damage from the collapse of the north tower, is on fire. Everyone in the building has already been evacuated.

4:25pm
The New York Stock Exchange, American Stock Exchange, and Nasdaq announce they will not open on Wednesday, September 12.

4:30pm
President Bush returns to Washington from Offutt Air Force Base in Nebraska.

5:20pm
Number 7 World Trade Center collapses.

6:10pm
Mayor Giuliani urges New Yorkers to stay at home on the next day, Wednesday, September 12.

7:45pm
New York's police department announces that at least 78 of its officers are missing. The city also announces that hundreds of firefighters have been killed.

8:31pm
In a televised address, President Bush says, "thousands of lives were suddenly ended by evil" and asks Americans to pray for the victims and their families. The president announces the U.S. government will not differentiate between terrorists and those who harbor them.

9:52pm
Mayor Giuliani announces that the city does not need any more volunteers for the immediate rescue work.

September 12, 2001
Four thousand FBI and CIA agents are involved in the investigation. Families report having received "goodbye" calls from loved ones who were victims of the terrorist attacks. All major league baseball games, NFL games, the Emmy Awards, and other major events postponed. For the first time NATO invokes Article V of the North Atlantic Treaty, which states that an armed attack on one member nation "shall be considered an attack against them all." Relatives and friends search for survivors in New York area hospitals. Americans across the country line up at blood donation centers. Flags fly at half-staff around the world. The U.S. financial markets are closed. All U.S. airports are closed.

September 13, 2001
Family and friends of World Trade Center victims fill out missing person reports at the Lexington Street Armory. Secretary of State Colin Powell names Osama bin Laden as the main suspect in the attacks. Mayor Giuliani estimates the attacks killed over 4,000 people in New York. The European Union declares Friday, September 14, a day of mourning. U.S. airports begin reopening; Boston's Logan and D.C.'s Reagan airports remain closed. U.S. bond markets open.

September 14, 2001
President Bush declares a national emergency. The Senate adopts a resolution authorizing the use of U.S. armed forces against those responsible for the attacks. President Bush visits the World Trade Center site. Federal officials release names of the 19 hijackers. Bush declares a "national day of prayer and remembrance." Many Americans attend religious services. Congress unanimously approves $40 billion for emergency aid, including $20 billion for New York. President Bush activates 50,000 national guard and reserve members to help with recovery and security.

September 15, 2001
President Bush meets with senior advisers at Camp David. Families of the missing are asked to bring in hairbrushes, razors, and other items for DNA analysis. Funeral services are held for New York City's Fire Department chief Peter Ganci, first deputy fire commissioner William Feehan, and department chaplain Father Mychal Judge.

September 16, 2001
A memorial service takes place at St. Patrick's Cathedral in New York City.

September 17, 2001
Much of Lower Manhattan reopens for business after a weekend clean-up. The New York Stock Exchange reopens for trading after its longest closing since 1933; the Dow-Jones logs its greatest absolute point loss in history, though not in relative terms. The major league baseball pennant race resumes. President Bush says Osama bin Laden is wanted "dead or alive."

September 18, 2001
A moment of silence is held at 8:48am EDT, exactly one week since the first plane struck the World Trade Center. "Reality of the chance of recovering anyone alive is very, very small," says Mayor Giuliani. The New York Stock Exchange rebounds with the help of retail and manufacturing companies.

October 2001
The Brooklyn-Battery Tunnel and many Lower Manhattan streets reopen to traffic. Governor Tom Ridge of Pennsylvania is sworn in as the first director of homeland security. President Bush signs a new antiterror bill.

November 2001
Estimates of the death toll at the World Trade Center, once as high as 6,500, are revised to fewer than 4,000. Newly appointed homeland security official Tom Ridge requests several billion dollars in funding.

December 2001
Congress authorizes an initial $8.2 billion in aid for New York City. A viewing platform opens at the site of the attack, now known as "Ground Zero." Thousands visit.

January 2002
Essential services are restored to the last parts of Lower Manhattan. The entire district, except for the block directly around Ground Zero, is reopened to full vehicular access.

March 2002
A pair of powerful upward-focused beams of light, located near Ground Zero and representing the twin towers, are trained on the skies each night throughout the month as a temporary memorial.

The following month, a memorial wall is proposed for the site when it is rebuilt.

May 2002
Workers conclude the recovery effort at Ground Zero. In 8-1/2 months, 1.8 million tons of debris have been moved to the Fresh Kills landfill on Staten Island.

May 28, 2002
The final girder from the World Trade Center is removed at a somber ceremony, marking the end of cleanup and recovery at Ground Zero.

June 2002
New York mayor Michael Bloomberg and the City Council agree on a budget they say will close the $5 billion deficit incurred as an economic aftershock of September 11. Ground Zero remains popular among tourists.

August 2002
Design plans for a new complex at the attack site are rejected and officials issue a request for new designs.

September 2002
The attack on the trade center will cost New York City $83 billion to $95 billion, according to the city comptroller. The number of people dead and missing at the World Trade Center is revised to 2,801, not including the hijackers.