Due to a mechanical error yesterday's story on Maryland's 21st Legislative District omitted the name of independent Democratic House of Delegates Candidate James A. Forsyth. Forsyth, 29, is a Laurel City councilmember. He has been endorsed by the AFL-CIO, the Teachers' Union and the Police Political Action Committee - the more endorsements than any other independent candidate in the District has received. The Washington Post incorrectly reported in Thursday's editions that a Carter administration proposal to give antirecession aid to cities is bottled up in a House Banking subcommittee.It is trapped in the House Government Operations subcommittee on inter-governmental relations and human resources.

To the casual observer, the only remarkable thing about Maryland's 21st Legislative District, wedged in the northwest corner of Prince George's County, is how little each block differs from the others. The rows of one-or two-story middle-class homes stretch almost unbroken from Laurel in the north to College Park in the south.

But to Prince George's County politicians, the 21st district is something of a curiosity. Politically, the only thing predictable about the place is its unpredictability.

Take, the case of Kay Bienen. In 1974, Bienen ran as an independent for a seat in the House of Delegates bucking the reputedly all-powerful Democratic Party organization. She won - easily.

This year, Bienen is running on the Democratic Party slate, but still is keeping complete control of her campaign. And her success of four years ago has spawned a host of imitators. Of the four people running for the districts Senate seat and the 13 running for the three House seats, 10 are running as independent Democrats. Almost all of these say they are running against what they call, "the machine."

"I think the voters in this district are less inclined to automatically vote for the slate than just about anywhere else in the county," said Bienen. "The voters here think about who their candidates are, not just who they are running with."

On this, if nothing else, all the candidates seem to agree. They see the presence of the sprawling University of Maryland campus in College Park and the Agricultural Department's testing station in Beltsville as major reasons for the district's independent outlook.

"I think having the university (of Maryland) here along with all the government employes makes this district quite a bit different than most," said incumbent Del, Pauline Menes. "The people here are very interested in the government, very involved. They ask a lot of questions."

It is that inquisitive nature, that sense of individuality, that the 13 candidates - including four Republicans - challenging the four incumbent Democrats are counting on this year. That, and the frustration felt in the district of 90,000 residents over rising tax assessments.

Besides having a higher average income than voters in most of the county's other legislative districts, the voters of the 21st - according to all the candidates - have an almost fanatical concern with their property tax assessments.

"Everyone's concerned with taxes everywhere," said Tim Maloney, a recent graduate of Georgetown University and an independent Democrat, who at 22, is the youngest candidate in the district. "But here, where property values are pretty high it goes further than that. When I knock on some people's doors, the first thing they do is whip out a calculator and explain how the tax relief program [evaded by the state legislature this year] really isn't worth a nickel to them."

Unlike the more southerly parts of Prince George's county, the 21st has not changed much since 1974. Development in th area, which already contains the cities of College Park, Laurel and Beltsville, has been minimal. The racial makeup of the largely white area has changed only slightly during the past decade, a time when there has been a marked increase in the county's black population.

And, aside from property taxes, ther appears to be no issue of overriding interest.

Thus, most of the challengers to the four Democratic incumbents, all of whom are seeking reelection, bring up two topics most often: the lack of tax relief for the community and their pet villain, the county's Democratic organization.

State Sen. Arthur Dorman and Dels, Bienan, Mones and Andrew O. Mothershead - the members of the organization slate - all say they are running on their records and the record of the Prince George's delegation the last four years.

"I think the fact that all we've heard from my opponents so far is 'Vote against the machine,' is proof that my record is a good one," Dorman said. "They don't have any issues to criticize me on so they fall back on that."

Democratic opponents in the Sept. 12 primary election, Leonard L. Colodny, George A. Leathers Jr. and Charles Wood all claim that the needs of the district would be served better if they replaced Dorman in Annapolis.

"With the problems we have and with many of the major bills being set up during the months that the legislature isn't in session we need a full-time senator, not a part-time one," said Leathers. (Dorman is an optometrist.) "You can't do the job during the 90 days the legislature is in session."

Wood said that he would make the organization's slate picking an issue. "The Democratic organization is an issue," he said. "The people should pick their own slate not have the party try and tell them what the slate should be."

Colodny, a former member of the county Human Relations Commission, charged that Dorman, is "controlled" by the organization. 'We have no leadership in this district. Art Dorman doesn't listen to the people, he listens to the organization because he owes his existence to them," Colodny said. "I'm in this race because I will provide leadership up there (Annapolis) for the people, not the organization."

The candidates see the newer arrivals as more liberal voters, the ones less likely to vote with the slate. Thus, the independents have pressed hard in the development areas, especially among younger voters.

"The young voters, the ones just out of college or still in college, can have a tremendous effect on this election if we can get them to vote," said independent Democratic delegate candidate Lawrence R. Albert, 25.

The organization also appears to be the major issue in the race for the three House of Delegates seats, where there are seven challengers to the three incumbent Democrats, and two Republican candidates who will automatically advance to the general election.

"I think the question people have to answer is, 'have the incumbents been effective in getting them what we all agree is needed in this district" said M. Neal Jacobs, a pharmacist seeking a delegate seat as a Democrat."The incumbents talk about tax relief, fine, but what have they done to get it for us?"

Democrats William C. DeLodovico Sr. and William W. Herndon have mounted aggressive door-to-door campaigns, arguing for tax relief and against the party organization.

In different words, but in much the same manner, Republican candidates Christopher T. Connolly and M. Jean Speicher and Senate Republican candidate Julia Brown are expected to run campaigns calling for "fresh blood," in the legislature in the November general election.

Virtually all the independents mention Bienen's victory in discussing their chances. "In this district everyone has a chance," Bienen said. "I don't think you can read the voters in this district. None of us will know who's run the best campaign until Sept. 12."