In 1933, the year Franklin Delano Roosevelt moved into the White House, a wealthy Winchester apple grower named Harry Flood Byrd Sr. was appointed to fill a vacancy in the U.S. Senate. The Byrd family has represented Virginia in Washington ever since.

But that era is about to end.

With the impending retirement of Byrd's son, Harry Jr., Virginia voters will go to the polls Tuesday to choose a new U.S. senator for the Byrd seat. The choice is between Paul S. Trible Jr. and Richard J. (Dick) Davis.

Trible, the Republican candidate, is a 35-year-old congressman from Newport News and a former Essex County commonwealth's attorney. Davis, the Democrat, is the state's 61-year-old lieutenant governor and a former mayor of Portsmouth.

Both candidates journeyed down different paths to their party's nomination. Trible, who has made no secret of his political ambitions, began planning a Senate campaign more than two years ago before Byrd announced his retirement. Davis, who was elected lieutenant governor last fall, shunned a Senate race until the Democratic party, wracked by intra-party squabbling this spring, was unable to find a candidate acceptable to all factions.

Both candidates have proclaimed themselves fiscal conservatives and have insisted they are the true heirs to the Byrd tradition. The electorate so far appears divided on the question. With pre-election polls showing Trible and Davis locked in a virtual dead heat, political experts are calling this the tightest Senate race in the country this year.

The Trible-Davis contest is the highlight of elections that include races for eight of the state's 10 congressional districts and, for the second year in a row, the 100-member House of Delegates. Voters also will be asked to consider three amendments to the Virginia Constitution.

In Northern Virginia, voters in Arlington and Fairfax County also will be asked to consider several local issues.

There is once again a rematch between Stanford E. (Stan) Parris and Herbert E. Harris II in the 8th congressionl District, which includes Alexandria, southern Fairfax County, eastern Prince William County and the northern tip of Stafford County. The two men have met twice before. In 1974, Democrat Harris beat Republican incumbent Parris. In 1980, Parris sought a rematch and ousted Harris. Now, the two political warriors are at it again.

In the 10th Congressional District, which includes Arlington, the northern half of Fairfax, Falls Church and Fairfax City and Loudoun County, Republican incumbent Frank Wolf is being challenged by Democrat Ira Lechner, an Arlington lawyer.

This is the second time in two years that voters will be electing delegates to the General Assembly and they'll have another chance a year from now. The General Assembly, attempting to redraw its boundaries to conform with population shifts revealed in the 1980 census, was unable to come up a map acceptable to the courts and the Justice Department in time for the 1981 vote.

The courts allowed the 1981 elections in temporary districts, but ordered the legislature to draw another redistricting plan and required the House members to run again this year. The new plan -- which puts all 100 House members into single-member districts -- has been approved by the courts. Northern Virginia voters who now live in districts represented by two or three delegates will be represented by only one in the future.

Also on the ballot are three proposed amendments to the state constitution, which will take effect in January, if approved. Question 1 proposes deleting references to marital status and occupation on state voter registration forms; the state Board of Elections says the information is not needed. Question 2 proposes authorizing the General Assembly to pass a law setting guidelines for the restoration of a convicted felon's civil rights. Currently, the governor makes such decisions on a case by case basis, after being peitioned by the individual felon.

Question 3 proposes imposing a limit on the introduction of legislation during the General Assembly's short (30-day) sessions every odd-numbered year. Legislative proponents say they are swamped with too many bills in too short a time.

Fairfax County voters will also decide three bond referendums for roads, park improvements and transit facilities.In Arlington, there is a referendum to create a local housing Authority.