As a young customs agent 15 years ago, Don. L. Smith chased the elusive smugglers over this hard and harsh scrubland along the Mexican border - the curios, the jewelry and the whatnots coming in, the American-made appliances, canned goods and other manufactured items going out.

He thought then, as he does now, that border-running had been a way of life for generations of people of Mexican ancestry whose language, families and culture were, like the warm winds blowing across thr Rio Grande, ungoverned by the invisible line dividing two nations.

So in the early 1970s, it was not unexpected in south Texas that the way to the good life began to center on this fact: Marijuana could be bought on the Mexican side and sold on the American at double the price - thousands of pounds of it at a time for distribution in cities across the Untied States.

Smith, now chief of the Drug Enforcement Administration office for this area, says as he drives U.S. Rte. 83 north from Rio Grande City to Roma: "The whole area is used for drug smuggling, but this part of 83 is the major area."

For many of the people of Starr County, population 17,707, more than half of whom were desperately poor, prosperity came.

Of course, not every affluent household in Starr is the fruit of crime. Many are the homes of legitimate businessmen, local employees and longtime-landed families.

But whatever the source pickup trucks, weighted with options, soled with wide treads and mag wheels and decorated with murals, multiplied on the unnamed, unpaved back roads.

Among the shabby shacks along Rte. 83 sprang sprawling ramblers, imposing split-levels and brick bungalows. There were cars on the dirt aprons out front - new ones and big - and so-called field workers became ranchers, while businesses prospered either on illicit earnings or the purchases they made possible.

"Estimates have placed from 10 to 35 per cent of the population of Starr County as being actively involved in the narcotics trade," an outraged Starr County grand jury declared in January after years of official indifference to the trafficking that was doing so much toward supplying America with marijuana and, to a lesser extent, heroin.

"There was so much money to be made off this marijuana business that it tended to corrupt [Starr County] society," says Assistant U.S. Attorney John Smith in Brownsville.

(Some) of these traffickers utilized as staging points vast landholdings in Mexico which were owned by their blood relatives," adds Peter B. Bensinger of the DEA. "From these holdings, large quantities of drugs were brought up from the interior of Mexico to be smuggled into the United States . . . According to our conservative estimate, approximately 7 1/2 tons of marijuana and five kilograms (11 pounds) of heroin passed through Starr County every week."

So brazen had illicit narcotics trade become that Starr County smugglers began to take pride in wearing a "uniform," says prosecutor Smith. They were a bullrider cowboy hat shaped just right with a feather or snakeskin band for decoration, expensive leather cowboy boots and laundry-pressed Levis.

Recently one man was arrested for allegedly trying to steal back from the state impounding lot 1,500 pounds of marijuana police had seized.

Starr County thus became synonymous with drugs, illegal wealth and ineffective or nonexistent law enforcement.

But after the county grand jury's call for help, Texas and federal drug enforcement officials, with unprecedented cooperation from Mexican authorities, began a major investigation of Starr County drug activities aimed at identifying the leader: "the ones who profit but who have not previously suffered the consequences," as DEA's Smith put it.

In April, the authorities swept in with 62 indictments alleging narcotics conspiracies involving 14 family-based organizations, most of them in Starr County.

High bonds were met with substantial cash deposits - $10,000 and $20,000 in many cases. Jose Francisco Mireles, who has his occupation listed as "trucker" and his wife, Velma, covered a total of $300,000 in bonds with property they own. (They have since pleaded guilty to one conspiracy charge each.)

Last week the Internal Revenue Service accused one of those arrested, Jose Guadalupe Garza, of earning at least $54,473.12 in 1974 but failing to file a tax return and failing to pay what the IRS calculated to be $11,151.60 in taxes. Starr County land records say that Garza who again is listed as "a trucker," owns 631 acres of land in the county. He is scheduled to stand trial today.

The indictments described an alleged pattern of narcotics business across the county, in neighboring Hidalgo County County and across the border, including: Drug-trade traffic into Mexico at official checkpoints and back through them as at the Rio Grande City, Roma and Falcon Dam crossing.

Unofficial crossings of the Rio Grande, which, at this point, is a wandering stream perhaps 100 feet wide but with depths ranging from ankle deep, in boats and rafts loaded with gunny sacks containing pressed bricks of marijuana or in recreational vehicles with hidden compartments.

Meetings arranged in a carwash, a motel, a restaurant, a fast-food stop or just along the road, be it Rte. 83 or a back dirt road leading to who-knows-where, but probably to the Rio Grande.

Exploiting the hundred miles of border along Starr and Hidalgo Counties and shipping large cargoes of drugs north in trucks only partially loaded with South Texas citrus.

Starr County has 15 sheriff's deputies. According to Neal Duvall, an assistant attorney general with state's Organized Crime Division, five of them were honorary deputies and basically ineffective. The others earned low pay ($350 a month) and say they operated under the belief they were not to pursue narcotics cases because they were untrained for such work.

One deputy was arrested over the July 4 weekend on charges of possessing 1,500 pounds of marijuana.

The judge, for most of that time, was O.P. Carrillo until his removal from the bench by the Texas Legislature for abuse of office a tax law conviction, which is under appeal.

It is significant that the local grand jury that finally called out for help was named by Carrillo's temporary successor - a judge from another county. The grand jury was named last September, and in January issued a lengthy, single-spaced list of findings and recommendations.

"Most (witnesses) agree that the problem has grown to such proportions and local law enforcement capabilities are so limited they are unable to cope with the situation," reported the grand jury, headed by Border Patrolman Herman Railey. "Other witnesses were thereafter summoned to testify within specific areas of concern usch as the involvement of law enforcement officials in narcotic traffic, failure of law enforcement agencies to aggressively participate in any narcotic suspension program, causes for breakdown in judical prosecution of criminal cases and in particular narcotic related cases . . ."

The chief of the Roma city police resigned the day after his appearance before the grand jury.

Officials attribute the aggressive work by the grand jury to "an unusual combination of people - 11 of the 12 were Mexican Americans and all spoke out at some risk.

One juror said the group of hard-working, law-abiding and tax-paying citizens had just grown tired of the splashy show of illegal wealth an the impact of widespread criminal activity on the community and children in which they take pride.

But in addition, 10 DEA agents worked full-time for four months with help from 21 others working part time. Texas officials supplied state troopers and other investigators. The local grand jury cited state Attorney General John Hill as being particularly effective.

Smith of the DIA cited unusual cooperation of the Mexican federal judicial police in identifying sources of drugs and the alleged traffickers.

When the dust settled, 116 persons were under arrest, many of them classed as major violators. The total cache was 40 tons of marijuana and almost seven pounds of heroin.

But whatever the federal-state-Mexican strike force accomplished, it did not halt the flow of drugs in Starr County. The 500-pound, 1,000-pound and 1,500-pound seizurres continue, and some officials attribute the continued traffic to some of the same people arrested in April.

And while drug trafficking stood out in Starr County because of the fortune it produced among poverty, officials agree that adjoining Hidalgo County has a far larger drug trade, the earnings from which blend more easily into a general affluence there from agriculture, tourism and business.

Few people think that the relatively small drug force here - DEA has 24 agents, few of them Chicano or fluent in Spanish and handling about 65 cases a month - will ever make major inroads into the business.

And one drug agent confided that he sympathizes with Mexican authorities who say the problem is not the supply in Mexico but the demand in the United States for drugs.

So what has it all meant?

"The good guys finally scored one," answers one resident.But that person is still frightened by the county he lives in, and his voice quavers as he asks not to be identified.