The nation's unemployment rate dropped to 6.1 per cent last month, the lowest since October 1974, the Labor Department said yesterday.

The rate, which was 6.3 per cent in January, has now fallen four months in a row. It was 7.6 per cent a year ago, in the Carter administration's first full month in office.

A White House spokesman described the president as being pleased by the statistics, which he said "support the view that the nation's economic fundamentals are still good" and that the economy is surviving the winter weather and the coal strike "reasonably well."

But the good unemployment news follows by a day some bad news on the inflation front: the Labor Department said Thursday that wholesale prices rose 1.1 per cent last month, the most in three years.

The government said the number of jobs in the expanding economy increased 122,000 by one measure, 350,000 by another, in February.

So far, the coal strike appears to be having a small effect.

Commissioner of Labor Statistic Julius Shiskin said that 25,400 factory workers were laid off last week in the 11 states most dependent on coal, but he noted that "these layoffs remained a small proportion of the 7.8 million factory workers in these 11 states."

Another 20,000 workers in teh railroad, barge and truck industries that handle coal have been laid off, almost since the start of the strike.

Shiskin told the Joint Economic Committee that the Labor Department is conducting a weekly survey of 1,000 firms in states such as Ohio and Indiana to monitor the impact of the coal strike on the economy.

Nearly all segments of the labor force reported lower unemployment rates in February, with teenagers the exception. The teenage unemployment rate rose from 16 percent to 17.4 percent , with all of the increase occurring among white adolescents.

The jobless picture was so much better last month than a year ago that even AFL-CIO President George Meany as moved to release a positive statement, although warning that the unemployment rate is actually much higher than the official 6.1 percent.

Meany called the February report "encouraging news. It demonstrates that economic stimulus programs do work."

Meany said, however, that the special jobs programs that were part of the economic stimulus package of 1977 are starting to wind down and said "additional economic stimulus program must be enacted to continue the direct attack on unemployment."

Much of the improvement in the employment picture occurred in non-agricultural jobs, especially manufacturing.

The unemployment rate is derived from a monthly survey of 56,000 households. It showed a gain in employment of 122,000 workers.

Another survey, based on a survey of manufacturers' payrolls, showed a gain of 350,000 jobs in February. The payroll survey is generally considered to be more accurate, although less inclusive, than the household survey in measuring month-to-month changes in employment. The payroll survey does not measure agricultural workers or self-employed workers.

The number of payroll jobs rose 3.1 million over the last 12 months. The number of total jobs in the economy as derived from the household survey grew 3.7 million.

While the total unemployment rate fell from 6.3 percent to 6.1 percent, the black unemployment rate fell sharply to 11.8 percent from 12.7 percent. The white unemployment rate fell from 5.5 to 5.3 percent.

While white teenage unemployment rose, black teenage unemployment felt from 38.7 percent to 38 percent.

The unemployment rate is that percentage of the labor force without a job but actively seeking one. The labor force is the sum of those with jobs and those seeking them. In February 93 million people had jobs an 6.1 million were unemployed.