A new signature at Treasury

Many Americans confuse the two positions. After all, there is the Secretary of the Treasury. Donald Regan now fills that powerful national economic post, in a tradition that goes back to Alexander Hamilton in the early days of the Republic. Then there is the other position, the Treasurer of the United States. The Treasurer's position is largely ceremonial, although it has been strengthened somewhat in recent years. But what gives the post special status is that the Treasurer's signature appears on all new US government currency.

The signature that will soon be going on all your new bills - assuming she is approved by the Senate, as expected - is that of Katherine D. Ortega.

Miss Ortega thus joins the long roster of other Treasurers (traditionally, a job given to women) whose names will be indelibly entered into national posterity. But unlike most other Treasurers, (including Treasurer Angela Buchanan who resigned in July), Miss Ortega is Hispanic, a factor that has clear political implications - but takes nothing away from the welcome all Americans should give her signature on their currency.

The White House now sees the Hispanic vote as crucial to Mr. Reagan's re-election effort. Mr. Reagan, according to some surveys, won 20 to 25 percent of the Hispanic vote in 1980. Administration officials now reckon that holding on to as many Hispanic voters as possible will be essential to offset anti-Reagan votes from women and blacks in the 1984 presidential contest.

Ironically, despite a new awareness of the Hispanic vote by both Republicans and Democrats, Miss Ortega is not the first woman of Hispanic background to hold the Treasurer's title. The first was Romana A. Banuelos, who was named by another Republican, President Nixon, back in 1971.

Miss Ortega, however, has already established her own record in ringing up a ''first'' - in her case, becoming the first woman bank president in the history of the state of California. She has also won numerous awards and founded and built up a $20 million savings and loan association in New Mexico.

An accountant, Miss Ortega sees her own Hispanic background as instrumental in explaining her success.

''I am the product.'' she says, ''of a heritage that teaches strong family devotion, a commitment to earning a livelihood by hard work, patience, determination and perseverance.''