What was going on when I was born?

The number of housing units in the United States increased at a rate more than double that of the population from 1970 to 1980, reflecting an accelerating trend toward fewer persons in each household, the Census Bureau reports. There was a net gain of almost 20 million housing units in the decade, a rise of 28 percent, while the nation's population rose 11.4 percent, to 226.5 million from 203.3 million. Preliminary figures from the April 1980 census reported 88,277,345 housing units, as against 68,704,320 in April 1970, an increase that many authorities considered unlikely at the beginning of the decade. Large Gains in West and Florida The Rocky Mountain states, Alaska and Florida experienced the highest rates in housing growth. Nevada led the nation, with a 96.8 percent increase, for a 1980 total of 340,000 housing units in the state; Arizona was up by 90 percent, to 1.1 million units; Alaska climbed 79 percent, to 162,400 units, and Florida was up by 72 percent, to 4.4 million units.

With Durand Macklin, their captain and leading scorer, in the locker room with an injured finger for most of the second half, Louisiana State maintained a large lead and beat Wichita State, 96-85, today in the Midwest regional final to earn a place in the Final Four of the National Collegiate Athletic Association basketball tournament. The left-handed Macklin, who scored 17 of his 21 points in the first half when the Tigers overwhelmed the Shockers, suffered a dislocated finger and required three stiches in his right hand. He sat out 12 minutes of the second half, first with leg cramps and then with the finger injury, but expected to be fit to play next weekend in Philadelphia. According to Dale Brown, coach of the 31-3 Tigers, the L.S.U. squad set five goals at a team meeting early in the season: to better last year's 26-6 record, to win the Southeast Conference title, to receive an N.C.A.A. bid, to make the Final Four and to win a national championship.

DENVER THE Mount Evans Hill Climb is an arduous 28-mile bicycle race that ends on the highest paved road in the United States - 14,264 feet above sea level. Bob Cook holds the record for the race: one hour 54 minutes 27 seconds. He won it the last six times, a feat easily comparable to the three consecutive Boston Marathons won by Bill Rodgers. A member of the 1980 United States Olympic cycling team, Cook will not defend his Hill Climb crown July 11. He died March 11 at the age of 23, having suffered the effects of brain tumors for three months. Ellen Cook said she never told her son that there was no hope after doctors diagnosed his problem as metastatic melanoma. ''Bob tried to hide the pain,'' said John Beveridge, an alfalfa and bean sprouts grower who sponsored Cook's racing team. ''I visited one day and asked him to do something. He was in bed and said, 'I'll have to think about that John.' And then he pulled the covers over his head and said, 'I do my best thinking under here.' In fact, I think he pulled up the covers because he was grimacing to hide pain.''

Six years after the Vietnam War, the Government's principal study of the war's effect on the lives of Vietnam combat veterans has concluded that they are plagued by ''significantly more'' emotional, social, educational and job-related problems than those who were not in battle. The study, a $2 million, eight-year investigation conducted by a New York-based research team for the Veterans Administration, confirmed the findings of earlier inquiries suggesting that exposure to combat had a direct relationship to current abuse of alcohol and drugs as well as to arrests, medical troubles and stress-related emotional problems. Veterans who are black or members of other minority groups were found to be strikingly disadvantaged in postwar schooling, careers and earning power, and with most veterans now in their mid-30's, the study concluded that most career setbacks may be irrevocable. Many Found to Be Strengthened It also found, however, that many veterans had been strengthened by their Vietnam experiences and were inclined to ''work through'' rather than suppress difficult problems. A total of 2.8 million Americans are veterans of the war in Vietnam, which began in the early 1960's and ended in April 1975, with the capture of Saigon by Communist forces.

''The idea that's been established over the last 10 years, that almost in life ought to be provided, financed by the Government as a matter of basic right, is wrong.

For the three seasons that Jim Lynam has coached basketball at St. Joseph's, the concept has been called four-to-score. It's a delay offense that was supposed to carry the Hawks home to Philadelphia and the Final Four. But there was a problem. Indiana's Hoosiers were unwilling to become, tall, frustrated chess pieces. Driven by the noise of the fans in their Assembly Hall, and more significantly by their coach, Bobby Knight, they quickly made the Hawks' concept unworkable and rolled to a 78-46 victory in the National Collegiate Mideast Regional championship game today.

Here beside the Red Sea, 20,000 foreign workers are building a $30 billion industrial city of refineries, petrochemical plants, oil storage tanks and piers for supertankers. On the Persian Gulf a thousand miles to the east, another industrial city is rising at Al Jubail at a projected cost of $50 billion; 30,000 foreigners are doing the work. The projects are part of an ambitious surge of development by Saudi Arabia, the world's leading exporter of crude oil and a major importer of foreign labor. The desert kingdom, which has roughly a fourth of the world's proven oil reserves and provides the United States with over a fifth of its crude oil imports, has about eight million people. But only 5.5 million of them are Saudis. The 2.5 million others are foreigners, and their numbers are expected to rise.

The Hecla Mining Company has offered to acquire Day Mines Inc. in an exchange of stock valued at about $165 million. Completion of the transaction would make Hecla the nation's largest silver producer. Under the merger proposal, Day shareholders would receive 1.65 shares of Hecla common stock for each of their shares. The action would come after a 3-for-2 Hecla stock split planned for Tuesday.

Paul A. Volcker, chairman of the Federal Reserve, promised some results in the inflation battle by the end of the year. But he said it was too much to expect consumer prices to be held to the 8.3 percent rate projected by the Administration for 1982. (Page A1.)

After a 22-year legal battle over the estate of the composer Bela Bartok, a decision is near in Manhattan Surrogate's Court on whether to award $1.3 million in ''legal fees and expenses'' to the composer's son Peter, a sound recording technician who has been representing himself in the case. When Bartok died in Manhattan 35 years ago, he left an estate valued at less than $10,000 and without enough cash to pay for his burial. Today his music is performed all over the world, yielding royalties that have recently averaged $100,000 a year. His birth in Hungary on March 25, 1881 is being celebrated internationally this year with centennial concerts and new recordings that are bound to swell the revenues of the Bartok estate. Bartok willed his property in Hungary and elsewhere outside the United States to Bela Jr., his son by his first wife. He left ''all the rest,'' including the rights to his music, in trust.

Union and coal company negotiators returned to the bargaining table at 1:45 A.M. today in a surprise resumption of stalled contract talks that, even if successful, cannot avoid a strike on Friday by 160,000 miners. The effect of a bargaining breakthrough between the United Mine Workers of America and the Bituminous Coal Operators Association would be to shorten an expected strike to days or weeks, rather than the indeterminate The threatened coal strike has lost some of its impact. Page D1. walkout predicted by the union when talks were halted last Tuesday. Sam Church Jr., president of the miners' union, has said that a strike this year could surpass the record 111-day walkout of three winters ago.

The Securities and Exchange Commission and the Commodity Futures Trading Commission have been engaged, virtually since the founding of the futures agency in 1975, in a jurisdictional battle little noticed outside of their respective regulated fields. This battle, involving such esoteric financial instruments as options on Government-guaranteed mortgage certificates and futures and options contracts on Government securities and foreign currencies, is part of a larger philosophical struggle over the regulation of the futures market, the least-regulated and fastestgrowing financial market in the country. Now, as a result of recent political and economic developments, the regulation of the futures market is attracting public attention on several new fronts. Further Hearings Scheduled Democrats in Congress, spurred by last year's silver crisis, which was precipitated by the wealthy Hunt family, are conducting an intensive investigation into the futures market in general and the silver market in particular, with further hearings scheduled for next month. Another impetus for the Congressional concern, the broader economic implications of overspeculation in futures on capital formation and credit allocation, is also receiving attention from several Government agencies, including the Treasury Department and the Federal Reserve. An interagency report, commissioned by Congress last year, is due to be completed in a couple of months.