Just read H. Paul Jeffers' An Honest President, a biography of Grover Cleveland, who served first 1885 to 1889, then from 1893 to 1897, the only president elected to non-consecutive terms. Cleveland saw, in his lifetime, both Abraham Lincoln and James Garfield shot before he attained the presidency, and after he left it, McKinley, the succeeding president, was shot near the end of his term, leading to Teddy Roosevelt's ascent from VP.

This information I find relevant just because growing up I remember hearing, "After JFK, no president would ever risk himself like that again," and I find it interesting to consider the cultural differences over time. One of our twentieth century presidents got shot and we've only piled on more security; in comparison, after the assassination of two presidents, including Lincoln, the following is still the description used for the White House of the late nineteenth century.

In a world where freedom was scarce and dreams of it scarcer, no on had coined for the president of the United States the phrase "leader of the free world." Fireside chats of Franklin D. Roosevelt via the radio were fifty years in the future and an address by a president ton television from "the Oval Office" was, like that chamber itself, unimaginable. Indeed, eight years after the twenty-second president of the United States into the mansion at 1600 Pennsylvania Avenue, the first edition of the traveler's guide Baedeker's United States 1893 saw "Executive Mansion of the President of the United States as so unimpressive that it was afforded one paragraph.

A sentence in that text, read more than a hundred years later, profoundly illustrated the changes which have occurred in the intervening century. The guidebook noted, "The East Room is open to the public from 10 to 2. Two or three times a week the President received all comers here at 1 p.m., shaking hands with each as they pass him in single file.

There was no White House "visitors' center" with metal detectors to screen those who came. No tickets. No eagle-eyed Secret Service agents in uniforms and plain clothes scanned the line of callers for the potential assassin. Nor was there an electric security system, a tall iron fence turning a presidential residence and offices into a "compound," or sentries at gates, assorted color-coded passes to be displayed on clothing, antiaircraft and missile defenses on the roof, sharpshooters and barriers closing Pennsylvania Avenue and other surrounding streets to traffic. A citizen was free, if he or she desired, to walk right up the lane or across the front lawn and up to the front door unchallenged. [Note: In another portion of the book, he mentions stories of Cleveland himself coming to answer knocks on the White House door.] The white mansion stood alone, unextended by east and west wings to accommodate staffs of the president and the first lady. No swimming pool. No room set aside for reporters. No photo ops. Not even a press secretary.

...

"There were no bodyguards. On many occasions foot excusions were made alone across the unfenced south lawn (where band concers were held in the summer) for strolls around the recently completed Washington Monument.

Per the White House Historical association, during the presidency of Benjamin Harrison (who was the president between Cleveland's two terms), in 1891, "An intruder climbed on to the South Portico and into the Red Room; he was restrained and held down by guards and President Benjamin Harrison." [Emphasis mine.]

Admittedly, it was during Cleveland's second term, as a result of the violence associated with the Pullman strikes, Coxey's army, and other social unrest, that White House security began to get ratcheted up, so this is even roughly around the time that guardianship of the presidency is starting to change. Still, though, fifty years later, you've got an assassin who almost gets to Harry Truman while he's napping in his underwear, so, you know, maybe not quite as much progress as you might expect in those intervening years.

Sources:

White House Historical Association

H. Paul Jeffers, An Honest President