For months, America's pundits have assumed that after a few noisy sideshows, the presidential election in 2016 would settle down into a contest between a Bush and a Clinton, two names that have featured in every presidential cycle since 1980. These are our dynasties — and our politics as well as our economy, historian Rick Perlstein argues in the Financial Times, is simply dynastic. Perhaps the appeal of Donald Trump or other non-politician candidates is a reaction to all the dynasties.

Republican donors and supporters of John Ellis Bush, the former governor of Florida known as Jeb!, might well have been betting on the dynastic tendencies of American politics. But while there are many local political dynasties that cross centuries (the Frelinghuysens of New Jersey, for example, or the Chafees of Rhode Island), and many dynasties of wealth, there is really only one true dynasty of national politics: the Bushes. The Clintons, with only one generation and one president so far, barely merit consideration. Measured by electoral success at the statewide or national level, even the names that come first to mind when you think of American political dynasties don't approach the reach of the Bushes, across four states and now grooming the fourth generation (which includes Texas Land Commissioner George P. Bush) and seeking their third presidency. But all dynasties seem to fade by the third generation or so, and even the most successful and deliberate of them eventually lose either the ambition or the luck to get elected. Jeb's current single-digit standing in the polls could mark the end of this family's singular success.

Here are some of the rivals to the Bushes, measured by electoral success:

The Adamses. Until the two George Bushes, John Adams and John Quincy Adams were the only parent/child presidents. They stand at the pinnacle of the Boston Brahmin elite, and the Adams family tree includes such prominent figures as Henry Adams (if you were assigned to read The Autobiography of Henry Adams in school and didn't get into it, please try again); Charles Francis Adams, who ran for vice president in 1848 on the Free Soil Party ticket; and Brooks Adams, an important historian. But only John and John Quincy achieved any office higher than member of Congress.

Until the two George Bushes, John Adams and John Quincy Adams were the only parent/child presidents. They stand at the pinnacle of the Boston Brahmin elite, and the Adams family tree includes such prominent figures as Henry Adams (if you were assigned to read in school and didn't get into it, please try again); Charles Francis Adams, who ran for vice president in 1848 on the Free Soil Party ticket; and Brooks Adams, an important historian. But only John and John Quincy achieved any office higher than member of Congress. The Harrisons. William Henry Harrison, the ninth president, who served just 32 days in office after contracting pneumonia at his inauguration, was the grandfather of Benjamin Harrison, who served two full terms in that blur of bearded presidents of the 1880s and 1890s. But with 47 years between the two inaugurations, it's hard to see the Harrisons as a continuous dynasty, even though Benjamin's father — the only person, so far, to be both the child and the parent of a US president — served four years in Congress.

William Henry Harrison, the ninth president, who served just 32 days in office after contracting pneumonia at his inauguration, was the grandfather of Benjamin Harrison, who served two full terms in that blur of bearded presidents of the 1880s and 1890s. But with 47 years between the two inaugurations, it's hard to see the Harrisons as a continuous dynasty, even though Benjamin's father — the only person, so far, to be both the child and the parent of a US president — served four years in Congress. The Roosevelts. The third family with two presidents, although distantly related. As Ken Burns's documentary about the family showed, FDR was in many ways inspired by Theodore, but 28 years elapsed between Teddy's reelection in 1904 and FDR's first victory, and they represented different parties, so FDR was not drawing directly on Teddy's coalition. Of Franklin and Eleanor's children, James Roosevelt served five terms in the House and ran for governor of California and mayor of Los Angeles, but lost both races, the first to future Chief Justice Earl Warren.

The third family with two presidents, although distantly related. As Ken Burns's documentary about the family showed, FDR was in many ways inspired by Theodore, but 28 years elapsed between Teddy's reelection in 1904 and FDR's first victory, and they represented different parties, so FDR was not drawing directly on Teddy's coalition. Of Franklin and Eleanor's children, James Roosevelt served five terms in the House and ran for governor of California and mayor of Los Angeles, but lost both races, the first to future Chief Justice Earl Warren. The Rockefellers. As a dynasty of wealth and philanthropy, the Rockefellers have no match, and at one time they had accumulated impressive political power as well. Nelson Rockefeller was governor of New York, a presidential prospect in 1964 and 1968, and eventually Gerald Ford's appointed vice president, where his most significant accomplishment was paying for the renovations of the vice president's mansion at the Naval Observatory. Winthrop Rockefeller was governor of Arkansas, and John D. Rockefeller IV, a Democrat, was governor and — until early this year — senator from West Virginia. (One current governor has a Rockefeller family connection: Gov. Mark Dayton of Minnesota was married to Alida Messinger, a sister of Jay Rockefeller.)

As a dynasty of wealth and philanthropy, the Rockefellers have no match, and at one time they had accumulated impressive political power as well. Nelson Rockefeller was governor of New York, a presidential prospect in 1964 and 1968, and eventually Gerald Ford's appointed vice president, where his most significant accomplishment was paying for the renovations of the vice president's mansion at the Naval Observatory. Winthrop Rockefeller was governor of Arkansas, and John D. Rockefeller IV, a Democrat, was governor and — until early this year — senator from West Virginia. (One current governor has a Rockefeller family connection: Gov. Mark Dayton of Minnesota was married to Alida Messinger, a sister of Jay Rockefeller.) The Udalls and the Romneys. I put them together because both are large Mormon families winning elections across several different states. There were three Udall cousins in the Senate recently, including Mark Udall of Colorado, Tom Udall from New Mexico, and Gordon Smith of Oregon. George and Mitt Romney were both governors and presidential candidates, and Rep. Morris Udall was the liberal favorite in the 1976 Democratic contest. But neither family produced a president.

I put them together because both are large Mormon families winning elections across several different states. There were three Udall cousins in the Senate recently, including Mark Udall of Colorado, Tom Udall from New Mexico, and Gordon Smith of Oregon. George and Mitt Romney were both governors and presidential candidates, and Rep. Morris Udall was the liberal favorite in the 1976 Democratic contest. But neither family produced a president. The Kennedys. For almost anyone over 40, especially those of us from the cities in the Northeast where a framed photo of JFK occupied a place next to the crucifix in many homes, it's a given that the Kennedy family is our central political dynasty, loved and hated. Yes, there's been only one President Kennedy, but there's so much lost promise: How much longer than 1,000 days might that presidency have lasted, and how many more President Kennedys might there have been? From 1956, when JFK almost captured the vice presidential nomination, through 1980, when Ted Kennedy's challenge to Jimmy Carter faltered, Kennedys loomed over every presidential contest, as either announced or potential candidates. With the exception of the brief period when Ted Kennedy wasn't yet old enough to serve in the Senate and a family factotum kept the Massachusetts seat warm for him, a Kennedy —or two — served in the upper house continuously from 1953 until Ted Kennedy's death in 2009.

But the third generation of Kennedys, now solidly into middle age, has not yet extended the dynasty at nearly the same level. Joseph Kennedy II (one of RFK's children) served five terms in the House, and his son, now 35, was elected to the same seat in 2014. Of Ted Kennedy's children, Patrick served several terms in the House from Rhode Island, and Ted Kennedy Jr. resisted politics but eventually sought and last year won a state Senate seat in Connecticut. Kathleen Kennedy Townsend served as lieutenant governor of Maryland but failed to capture that blue state's governorship in 2002. Their public service is admirable (as is that of Caroline Kennedy, the US ambassador to Japan, and the Shrivers), but measured purely by electoral success, these third- and fourth-generation Kennedys hardly dominate American politics in the way they were once expected to.

The Bush dynasty, on the other hand, begins with Prescott, senator from Connecticut in the 1950s (some accounts of the family ascribe a major role to Prescott's father-in-law, George Herbert Walker, a Wall Street grandee), and continues with George H.W. Bush, elected to the House in 1966 and then mostly appointed to positions until running for president in 1980 and being selected as Ronald Reagan's running mate. A Bush has been on every successful Republican ticket since, and George's sons won the governorships of the second and third largest states. (In a kind of diversified investment strategy, a third brother, Neil, once thought to harbor great promise, was sent to Colorado, another state that would be critical to the conservative Republican counterrevolution.) No family comes close to that level of political success, across generations, across states, shifting ideology as needed to win.

The United States surely has a problem of dynastic economic power and dynastic control of access to elite institutions. But our politics, which has produced presidents named Obama, Clinton, Reagan, Nixon, and Johnson, who started with nothing, is not all that dynastic. Mostly there are just too many Bushes.