What was going on when I was born?

After more than 42 years of uncertainty, 670 families in Broad Channel, Queens, will be able to buy the land their homes are on, city officials announced yesterday. Since 1939, when the city regained control of the land from a development company that went bankrupt, owners of the area's clapboard homes have lived under a threat of eviction. The city leased the land to the residents and had the option to terminate the leases at the end of each year on 10 days' notice. But yesterday, the Board of Estimate voted to sell the land to residents of the three-mile-by-two-block area on Broad Channel Island, Jamaica Bay's only inhabited island.

On the battered streets of west Beirut today weary guerrillas lounged in the shade, apparently resigned to being scattered to other Arab countries. Civilians, the innocent victims of the fighting here, began venturing back into the streets as the Israeli blockade eased, and a few stores opened their steel shutters. More and more fruit and vegetables were being displayed on carts and sidewalks, and a Red Cross convoy carrying 40 tons of food and thousands of gallons of fuel was allowed into west Beirut by the Israelis. But the mood was cautious at best, as people feared that any incident could set off a new and even more violent round of warfare.

The Israeli Cabinet approved a plan today for the withdrawal of up to 15,000 Palestinian and Syrian fighters from west Beirut, ending a 10-week siege of the Moslem section of the city and opening a new chapter in the Middle East. The withdrawal plan, drafted by Philip C. Habib, President Reagan's special envoy, calls for the departure of the guerrillas to other Arab countries after the return of two captured Israeli soldiers. The pullout, which is expected to begin Saturday, is to be supervised by American, French and Italian troops. (The White House, saying it was ''extremely gratified'' by the Israeli Cabinet's approval of the plan, said the action ''sets the stage'' for a withdrawal of Palestinian and Syrian forces by as early as the weekend. Page A11.)

Mexico's acute financial problems sent international bankers scrambling yesterday to arrange a sweeping financial program intended to prevent the Government from running out of cash and to stop a run on the peso. Leading Mexican officials met with several New York banks yesterday in an effort to postpone at least some payments on about $40 billion of debt interest and principal that is due within a year. Meeting Scheduled Today The officials will meet today at the Federal Reserve Bank of New York with representatives of about 55 leading international banks from around the world. ''It's a who's who in the international bank list,'' said one banker who is to attend the meeting.

JAZZ as we know it began in New Orleans. Black musicians may have been improvising a jazzlike music in other cities and towns in the early years of this century, but Buddy Bolden, King Oliver, Jelly Roll Morton, Sidney Bechet, Louis Armstrong and the other innovators who stamped their identities on the new music and breathed life into it were all New Orleans men. Tonight and tomorrow night, at the Public Theater, a specially assembled group of New Orleans jazzmen, including the celebrated drummer Ed Blackwell and the formidable young trumpeter Wynton Marsalis, will be performing. They will not be playing the traditional jazz that most listeners still associate with the Crescent City. Although they are proud of and well versed in the rich heritage of their hometown, they are thoroughly modern musicians. Ed Blackwell has made many recordings with Ornette Coleman, John Coltrane and other innovators, and Wynton Marsalis records for Columbia. But most of the modern musicians in New Orleans have been ignored by record companies and jazz writers, and so has the New Orleans modern jazz scene. In fact, most jazz fans are surprised to hear that New Orleans has a modern-jazz scene and are more surprised to learn that New Orleans musicians played a key role in the development of free jazz in the late 1950's and early 1960's.

NEW YORK as a place for artists to work in has just about everything to recommend it. New York as a subject for art is something else altogether. Contrary to what is often supposed, painters have not often done well with it. The space, the scale, the contrasts and incongruities and contradictions - all work better in the movies, or in still photography, than in painting. It may be relevant that among the European painters of real substance who have come to New York and been carried away by it, barely a one ever tried to use it directly. Matisse, Leger, Magritte, Dubuffet - all had too much sense. There was, however, in the first half of this century, a New York subject that was just about infallible for artists, and it is being commemorated through Sept. 26 in an exhibition of prints, drawings and photographs at the Mary Ryan Gallery, 452 Columbus Avenue, at 82d Street. It has a great photograph by Berenice Abbott, some classic prints by John Sloan, Reginald Marsh, William Gropper, Isabel Bishop and others, a surprise by Franz Kline and a whole slew of images by artists who have been undeservedly forgotten.

A Reporter's Notebook: Weeks of seige In Brazil's wild northeast, there's no end to bloodletting A2 Taiwanese appear unmoved by U.S.-China accord A3 Marcos denounces BBC documentary on the Philippines A3 Falkland Islanders appeal to U.N. to stay with Britain A6 South African vote seen as rebuff to ruling party A7 120 nations at U.N. renew de- mand for Palestinian state A11 300 French legionnaires leave Corsica for Lebanon A11 Western Europe relieved by Israel's agreeing to pullout plan A11 In northern Israel, residents tell of hope, relief and skepticism A12 Soviet reaction to evacuation plan is cautious A15 Government/Politics Jersey candidates for Senate have been raising money B2 M.T.A. board approves issuing of $200 million in bonds B2 Representative Green describes pressure for support of tax bill B3 Lehrman and Curran question each other's character B3 General Two doctors charged with murder of Coast patient A8 F.B.I. seeks contact with kidnappers of abortion doctor A9 Around the Nation A17 Inquiry on acid spill focuses on possible truck corrosion B2 Ratings suspended on $350 million in state authority's bonds B3 Television networks facing crackdown in capital D16 Health/Science Soviet astronaut becomes second woman to travel in space A28 New Analysis Hedrick Smith discusses Reagan's tax victory D14 Weekend Weekender Guide C1 Seeing the Connecticut River Valley C24 Newport, R.I., is host to wooden-boat show C24 Music: A modern kind of New Orleans jazz in town C1 Charlie Haden, self-taught jazz bassist, is in demand C6 Ornette Coleman and Johnny Copeland at Seaport benefit C22 Art: Suburban museums offer summer pleasures C1 Memories of New York's El in gallery show C1 Auctions C24 Stage: Broadway C2 New Face: Christine Baranski in ''Midsummer'' C5 Screen: At the Movies C8 ''Six Pack,'' a Kenny Rogers movie C9 Hollywood unions seek safety panel C12 ''Summer Lovers'' from ''Blue Lagoon'' director C17 Dance: Kei Takei company performing in SoHo C19 Hans Leiter, an ice-dancing clown C28 Restaurants C20 Books: ''19 Purchase Street,'' international mystery, reviewed C25 Publishing C26 TV Weekend C26 Washington Talk Congress: A look at a session preoccupied with money A16 Program assists women of both parties running for office A16 George Washington's personal papers have a special place A16 Briefing A16 Style The Evening Hours B6 The Queen Elizabeth 2 steams in, festively refitted B6 Wraparounds by Halston B6 Obituaries Dr. Leonard Covello, longtime educator in East Harlem B4 Dr. Loyal Davis, surgeon and Nancy Reagan's stepfather B4 Quotation of the Day ''The Cabinet resolved to approve the amended draft of the arrangement submitted by Ambassador Habib concerning the departure of the terrorists, their organizations, their leaders, their members, their headquarters and their offices from Beirut and from Lebanon.'' - Dan Meridor, spokesman for the Israeli Cabinet. (A13:1.) Sports Pages Griffey seeking trade away from Yankees A19 Mets lose, 3-1, and fall into last place A19 Braves and Niekro beat Expos, 5-4 A19 Joe Morris, at 5-7, tries to be Giant at running back A19 Mercury Morris drug case expands A19 Mrs. Carner and Miss Stacy share golf lead 20 Scouting: Majoring in pocket billiards A20 Jim Kern's beard becomes a Cincinnati controversy A20 Owners remain divided over Bowie Kuhn's future A20 McEnroe advances in A.T.P. after losing first set A21 George Vecsey on Bowie Kuhn A21 Features/Notes Man in the News: Robert Clark, black Mississippi politician A18 Sports People A21 New York Day by Day B3 Editorials/Letters/Op-Ed Editorials A26 The P.L.O., under the rug Mr. Helms plays dodgem New seeds in the Delta Peter Passell: a market boom? Letters A26 Tom Wicker: taking aim at hand-guns A27 Flora Lewis: the politics of bigotry A27 Mohammed Sid-Ahmed: Egypt and Israel after Lebanon A27 Jonah Shacknai: Oraflex and the critics A27

Yields on Treasury bills plunged yesterday, reaching their lowest levels in two years, as rumors swept Wall Street that major banks in the United States were facing problems on loans to Mexico. The three-month Treasury bill plummeted a point - one of the sharpest declines in recent memory -to yield slightly less than 7 percent at the end of a tumultuous session. Its companion security, the six-month bill, fell almost as much in yield. The six-month bill dropped 93 basis points, or hundredths of a percentage point, to return slightly less than 8 1/2 percent to investors.

An avant-garde puppet group from Rio de Janeiro will make its New York debut depicting the lives of Brazilian Indians and peasants in ''Mansamente'' (''Softly''), a three-story play for adults, tonight and tomorrow and next Friday and Saturday at 11 P.M. in the Dance Theater Workshop's Economy Tires Theater series at 219 West 19th Street. The troupe, Grupo Contadores de Estorias (The Storytellers), speaks no words; a soundtrack of Brazilian songs and rhythms accompanies the action. Marcos and Rachel Ribas, manipulators of the puppets, wear black tights and hoods in the Japanese Bunraku manner. Tickets are $5. Reservations are recommended: 691-6500. NEWARK SILENT SCREEN Pearl White as a tightrope walker plummets from a high wire. Will she be saved? Episodes from the ''Perils of Pauline,'' the 1914 series of cliffhanger movies, will be shown free today and next Friday at 12:30 P.M., at the Newark Museum. There will be other silents made in New Jersey, a state that was the site for many productions of the early film industry. New Jersey, a museum spokesman explained, offered varied landscapes and was close to New York acting talent. The museum is at 49 Washington Street in downtown Newark. Information: (201) 733-6600.

The Occidental Petroleum Corporation told management of the Cities Service Company that it would consider paying as much as $52 a share for the company if the Cities board supported its takeover attempt, Occidental disclosed yesterday. Although Cities Service management would not consider the sweetened proposal, which Occidental said was made in advance of the formal $50-a-share offer that got underway yesterday, Cities shares soared $5.25 a share on the New York Stock Exchange, to end the day at $43.875, on a volume of 2.4 million shares. Wall Street traders said the advance was aided by reports that negotiations with other suitors appeared to be quickening in a bid to head off Occidental's unwelcome offer.

The popularity of money market funds may have peaked, experts said today, because of the sharp decline in shortterm interest rates and the sudden resurgence of the stock market. ''At some point, the money will start to flow back into long-term bonds and bank certificates,'' said David Dreman of Dreman, Grey & Embry Inc., a New York investment counseling firm. ''Some cash is also been parked in the money funds waiting to get into the stock market.'' To be sure, it is too early for any shrinkage to have shown up in the funds themselves. For the week ended Wednesday, one day after a spectacular rally in the credit markets that sent short-term interest rates plunging, assets of the nation's money market funds rose $3.43 billion, to $223.45 billion, the Investment Company Institute reported today. Since late June, the funds' assets have risen more than $20 billion.

Congress approved the $98.3 billion tax bill. Approval in the House, by a vote of 226 to 207, came first, after four hours of debate. Then the Senate took up the bill and voted 52 to 47 for the measure. (Page A1.) The vote was a dramatic victory for President Reagan. (D14.) The pace of voting was unusually swift for the House. (D14.) The economy grew at an annual rate of 1.3 percent in the second quarter after posting declines in the previous two periods, the Commerce Department said. The revised data were considered supportive of the view that the recession has bottomed out. (D3.)