[Binky Bainbridge]

Let's examine them one at a time:

Abraham Lincoln was elected to Congress in 1846.
John F. Kennedy was elected to Congress in 1946.
This statement is literally true: both Lincoln and Kennedy were first elected to Congress one hundred years apart. Aside from that minor coincidence, however, their political careers bore little resemblance to each other.

Abraham Lincoln was elected President in 1860.
John F. Kennedy was elected President in 1960.
It's hardly surprising that two men who (as noted above) both achieved their first political successes at the national level a hundred years apart would also ascend to the Presidency a hundred years apart. This "coincidence" is even less surprising when we consider that presidential elections are held only once every four years. Lincoln couldn't possibly have been elected President in 1857 or 1858 or 1859 or 1861 or 1862 or 1863, because no presidential elections were held in those years. Likewise, Kennedy couldn't possibly have been elected President in the non-election years of 1957, 1958, 1959, 1961, 1962, or 1963.

The names Lincoln and Kennedy each contain seven letters.
Surely this is the most trivial of coincidences, especially considering that the two men's first names contain different numbers of letters, and that Kennedy had a middle name (Fitzgerald) while Lincoln had none.

Both were particularly concerned with civil rights.
This is one of the statements that is so misleadingly worded (or downright inaccurate) that it doesn't really merit inclusion even on a list of mere superficial similarities.

Both wives lost their children while living in the White House.
Another statement that, while literally true, is misleading and masks much more substantial dissimilarities.

The circumstances and nature of the deaths alluded to here are completely different, and the way the statement is phrased ("Both wives lost their children") implies that both women suffered the misfortune of a stillbirth or the death of an infant, something that is true only of Mrs. Kennedy.

Both Presidents were shot on a Friday.
Another non-surprise. Absent all other factors, the odds were already one in seven that both killings would have occurred on the same day of the week.

Both were shot in the head.
This "coincidence" is just plain dumb. The only two types of shots which reasonably assure a dead victim are chest shots and head shots, so two assassinations committed by head shots aren't the least bit coincidental,

Lincoln's secretary, Kennedy, warned him not to go to Ford's Theatre.
Kennedy's secretary, Lincoln, warned him not to go to Dallas.
This is one of those coincidences that isn't a coincidence at all -- it's simply wrong. John Kennedy did have a secretary named Evelyn Lincoln (who may or may not have warned him about going to Dallas), but one searches in vain to find a Lincoln secretary named Kennedy. (Lincoln's White House secretaries were John G. Nicolay and John Hay.)

Both were assassinated by Southerners.
A dubious use of the term "Southerner." Although John Wilkes Booth was undeniably a Southern sympathizer, he was born in Maryland, which (along with Delaware) was the northernmost of the border slave states and remained part of the Union throughout the Civil War.

Both were succeeded by Southerners.
Both Lincoln and Kennedy were "succeeded by Southerners" because both had Southerners as vice-president, another fact hardly surprising considering the circumstances.

Both successors were named Johnson.
Given the high frequency of "Johnson" (literally "son of John") as a surname in both Lincoln's and Kennedy's time, this "coincidence" should be no real surprise to anyone.

Andrew Johnson, who succeeded Lincoln, was born in 1808.
Lyndon Johnson, who succeeded Kennedy, was born in 1908.
Another hundred-year coincidence that is hardly surprising, since nearly all American politicians have attained high office (President or Vice-President) while in the 50-70 age range (and Andrew Johnson and Lyndon Johnson were, obviously, contemporaries of Lincoln and Kennedy,

John Wilkes Booth was born in 1839.
Lee Harvey Oswald was born in 1939.
Another coincidence that is no coincidence because it's plain wrong: Booth was born in 1838, not 1839.

Both assassins were known by their three names.
Another "coincidence" of dubious veracity. John Wilkes Booth was often billed as "J. Wilkes Booth" or simply "John Wilkes" (primarily to distinguish himself from his father and brother -- both named Junius -- and his brother Edwin, all three of whom were also actors), and as a prominent actor, his name was already familiar to the general public at the time of Lincoln's assassination. Lee Oswald was generally referred to as "Lee" (not "Lee Harvey")

A month before Lincoln was assassinated he was in Monroe, Maryland.
A month before Kennedy was assassinated he was in Marilyn Monroe.
This is a latter-day addition to the list and nothing more than a bit of salacious humor. Even as a humorous coincidence it fails the test, as Marilyn Monroe died well over a year before Kennedy's assassination.