ANDREW JACKSON was so thoroughly American it's embarrassing, which may be why he's often left off the list of our great presidents. But Old Hickory saved the Union, redefined our democracy and set the United States on the course it still follows.

A thoughtful new exhibition at the National Portrait Gallery should go a long way toward altering our perception of Jackson as an uncouth backwoodsman and restoring him to the stature he once enjoyed.

Jackson was a self-made man, forged in cruel fires. Born dirt poor and fatherless, the son of Irish immigrants, he served as a teenager in the Revolutionary War, in which he was badly injured and lost his mother and both of his brothers. Jackson was a rowdy youth and grew into a quick-tempered man who bore to his grave bullets received in a duel and a gunfight.

But he became a lawyer, a respected judge and a prosperous planter. His quick mind and deep courage made him a brilliant natural general who snatched victory from defeat in the War of 1812.

Leading largely ragtag troops, he decisively defeated the Indian allies of Great Britain at Horseshoe Bend, Miss., and then destroyed at the Battle of New Orleans the British army that had whipped Napoleon and burned our national capital. If George Washington was the father of the country, Jackson was the son who won America full membership in the family of nations.

Jackson served in both House and Senate and should have been our sixth president. In 1824 he won the popular and electoral vote but not by the majority then required. The House, a gentlemen's club in those days, gave the mantle to Boston Brahmin John Quincy Adams.

But the man of the people was not to be denied. Jackson won the presidency outright in 1828, and soon was vigorously kicking butt. He not only balanced the budget, he paid off the national debt. Although swollen by the expenses of the war, by January 1835 the debt was retired for the first and only time. That same month he escaped the first would-be presidential assassin, a nut whose pistols misfired.

Jackson founded what became the Democratic Party and established the spoils system which, however abused, gave power and profit to the people. With him began the conversion of the country from an aristocracy to a meritocracy.

In 1832 Jackson blocked his native South Carolina's first try at secession, propounding the principle of the permanence of the Union upon which Lincoln would rely.

But our history was written by intellectuals who are much more comfortable with the noble Washington and the genteel Jefferson than with Jackson, the frontier brawler who threw open the doors of the White House to just anybody.

And of course anyone who considers Jackson's place in history must deal with the terrible and ineradicable stain of "the great Indian removal." Jackson, fearing that the presence of eastern Indians endangered national security, betrayed the Native Americans who had fought beside him in the Creek and Seminole wars, as well as peaceful, industrious and law-abiding members of the Five Civilized Tribes.

All alike were sent into exile or death, beginning what became a tacit national policy of genocide that culminated in the massacre at Wounded Knee.

But there's reason to believe Jackson hardened his heart out of a conviction that the Indians must go or be wiped out by white settlers, and he certainly did not intend the exodus to be the cruel death march known as the Trail of Tears.

And in any case few great men are entirely good men. Jackson showed many faces to the world, and this ambiguity is reflected in the fantastic range of portraits in this exhibition. We can be fairly confident of what most famous early Americans looked like, but no two of the seventy Jackson portraits on the gallery walls show the same man, whether the intention was to depict him as hero, saint or tyrant.

In his own time, Jackson's role was not in doubt. Curator James G. Barber makes a persuasive case that Jackson was the most popular president we've ever had. Even one of his opponents said, "No man ever lived . . . to whom the country was so indebted. Talk of him as the second Washington! Washington was only the first Jackson."

Like it or not, ours is not a Jeffersonian but a Jacksonian democracy. Old Hickory shoved us down the right path.

OLD HICKORY:

A Life Sketch of Andrew Jackson -- Through Jan. 13 at the National Portrait Gallery, Eighth and F streets NW. Open 10 to 5:30 daily. Metro: Gallery Place.