Despite economic gains over the past generation, the South still has the highest share of poor people of any region in the country, according to Census Bureau figures and a report released yesterday by the Southern Regional Council.

The Census Bureau, in a report last summer on poverty rates in 1983, found that 17.2 percent of the South's population was below the official poverty line of $10,178 for a family of four.

In the Northeast the figure was 13.4 percent, in the Midwest 14.6 percent and in the West 14.7 percent. The Census classifies 16 states and the District of Columbia as southern.

The Southern Regional Council (SRC), in a report yesterday, said the 11 states of the old "historical" South have a poverty rate of 18.2 percent, the highest in the nation, and the number of people in poverty is about 12 million, the same as it was 20 years ago. The SRC does not count as southern the District of Columbia nor five states included in the Census grouping: Maryland, Delaware, West Virgina, Kentucky and Oklahoma.

The SRC said the poverty count in the old 11-state South, rated in 1959 at 37.4 percent by the SRC, had declined steadily to just over 15 percent in 1979, but has been rising in recent years, also true for the rest of the nation.

Although the South still has the highest proportion of poor, the Census tables show that the gap between it and other regions has been narrowing.

In 1959, according to the Census, using its 16-state grouping, the rate for the South was 35.4 percent and for the North and West 16 percent; as late as 1970 the figures were 18.6 percent for the South and 10 percent for the North and West.

According to the SRC, about two blacks in every five in the South are in poverty.

Among families headed by black women, it said, the poverty rate "was probably higher than 60 percent in 1983."

The report disputed arguments that welfare aid discourages the poor from working, saying that in the South, "government benefits go overwhelmingly to the poor least able to work or to find work because of age, sex or family circumstances."

It said that in 1982, 95 percent of the households receiving cash benefits in the South were headed by a female parent with children, and 79 percent of all government benefits to the poor, both cash and in-kind benefits such as medical care and food stamps, went to such households or to persons 65 and over.