The data for this analysis comes from Nov. 21, 1993 to Jan. 1, 2025, totaling 11,365 puzzles and 949,106 clues, from XWordInfo.com, which contains puzzle information for every Times crossword ever published.

While the data from 1942 to 1992 is certainly useful, the date restrictions here are so that the observations are only from the Will Shortz era, when he edited the crossword. This just makes the stylistic choices of Shortz's puzzles more apparent in the data.

With over 11,365 puzzles in the dataset, there are bound to be repeating tile configurations. Below is the most common pattern, which appears 14 timesⁱ over the last 30 years:

In fact, nearly all of the puzzle tile patterns are unique:

Though this might be the case, there are still important insights to be gained from observing the placement of the white and black squares.

Below is a heatmap of the tile patterns of all 15x15 crosswords in the dataset. Though puzzle sizes vary over the week, there are 9,369 crosswords with these dimensions. The scale shows, for each tile, what percentage of crosswords have a black square in that location.

Notice how all of the corners of the grid are left empty, since one or two-letter answers are extremely rareⁱⁱ. Instead, there are clear borders around those areas, making three and four-letter words dominate those spaces.

Nearly all puzzles have rotational symmetry, which helps explain the pattern of white spaces in the middle, since placing a black square there would mean a one-letter answer would need to be in the center of the grid.

This pattern doesn't change much over the years, either.

Above is the same heatmap, smoothed over each year. Though there is some variance year to year, as a whole, the same pattern of rotational symmetry and white corners is visible throughoutⁱⁱⁱ.

There's plenty of insight to be gained from the text that fills the grid of the puzzle, too. Being bound to the constraints of the English language, certain words appear more frequently than others because of their flexibility.

Word structures that follow a "CVC" pattern, or a consonant, followed by a vowel, followed by another consonant, are the most commonly used in puzzle answers. Below is a table of the next 4 most frequent sound patterns:

Again, it follows that these are short words with standard and frequent vowels.

One way puzzle makers implement this difficulty is by including more novel words, as seen below. On the more difficult days of the week, common words are less likely to be seen, whereas early in the week, they're more abundant.

Sunday puzzles are an exception to this pattern, since the large size of the grid means more clues, so common words are more likely to be reused.

Another way of describing this pattern is by looking at the type-token ratio, which describes the lexical diversity of the puzzles by dividing the number of unique answers by the total number of answers.

The advertised difficultly is indeed correlated with lexical diversity: in a given year, over 90% of answers are unique between each Saturday variant of the puzzle, compared to only 80% with Mondays.^v

Aside from just using new words, puzzle creators also vary the length of answers^vi to achieve difficulty.

Here, the difference in difficulty is clear: more difficult puzzles tend to have longer answers. That also means they are less likely to repeat short answers, so length and lexical diversity go hand-in-hand.

Below is an ordered list of the most common clues in the crossword, paired with some of their answers.

The same can be said for a clue like "Up", which can be answered with ATBAT, ALOFT, or ASTIR. The most common clue, though, is significantly different: it references a specific grid location rather than being a descriptor of a word.

To understand why 17-Across is so special, take four puzzles that feature the clue.

In each of these grids, 17-Across is the first lengthy answer. These longer spaces are often used by puzzle makers to create a theme or shared answer, which connects over other, longer answers. However, the later clues do not need to repeat the same phrasing as the first, so they default to "See 17-Across".^vii

This phenomenon is best understood with an example. The 17-Across clue in the top right crossword of the previous diagram reads: "With 36- and 59-Across, words of Alexander Pope." Then, 36- and 59-Across, rather than repeat the same clue, both say "See 17-Across." The answers to these three clues are filled in below:

When complete, they reveal a quote stretched across all three answers: "Fools rush in where angels fear to tread."

Honing down to just the most common clue-answer pairs yields a slightly different result.

Interestingly, there's been a clear trend in how the Times chooses their clues: over the years, the average length of clues, in terms of the total number of characters^viii, has consistently increased, with little variation across different days:

It's unclear whether this corresponds with a particular change in difficulty. On one hand, longer clues increase context for an answer, but on the other, they can also increase complexity. Regardless, it's fascinating to see such a clear trend across time.

The Times crossword employs a lot of conventions in their clues. One of them pertains to clues enclosed in quotes ("..."). According to the Times, a clue written in this manner is "something someone might say out loud" and its answer is "a synonym for that verbalization".

For instance, a clue like "I goofed" has the answer MYBAD. The most common verbalizations are listed below:

Knowing the common answers to such clues can aid in solving: 72.4% of puzzles contain at least one of these "quote" clues.

Another convention of the crossword is clues that start and end with a square bracket ([...]). For these, the clues suggest answers that are non-verbal a clue like "[Get the joke?]" can be answered with WINK. Again, below are the most common answers:

While these types of clues appear in only 5% puzzles, whenever they do appear, it will be easy to draw upon the above word bank to solve.

There are also less "formal" quirks found within crossword clues, mainly revolving around their wording. Below is a table of the most frequently used first words (including special characters) in Times clues. A sample clue of each type is appended in gray:

To the untrained solver, these clues can seem purposefully confusing. However, they are really just ways for writers to reach certain types of words adjectives are paired with clues that begin with "Like" ("Like much of Sudan": ARID) and clues that start with "Kind" are answered with prefixes ("Kind of bean": SOY), for instance.

The same can be done for the last word in a clue:

Endings like "e.g." and "for one" require examples as answers ("Wonder Woman, for one": HEROINE), and the endings "Abbr." and "for short" are paired with abbreviated phrases ("Las Vegas's home: Abbr.": NEV).

Other endings like "say", "maybe", and "in a way" can vary in their use cases, but typically involve a non-straightforward answer ("No credit, say": CASHONLY)^ix.

Though it might seem like the crossword follows a certain formula, there is still plenty of room for growth. For instance, the references that the Times makes in their clues have significantly varied over time:

Take the above chart, which shows the person referenced by clues that had the answer ADELE. Before Adele (the singer) became a household name, the answer was still used in the crossword for its relatively short length and high vowel count, with references to other (lesser-known) Adeles^x. But after Adele began releasing albums, the crossword clues immediately pivoted to utilizing her identity as a sole reference.

Even still, answers also have the potential for variance over time.

While not as common an answer as ADELE, likely for its slightly longer length and lower vowel density, SERENA has appeared 39 times after Serena Williams (the tennis player) won the U.S. Open in 1999. More importantly, SERENA hadn't appeared once in the six years prior to her stepping onto the global stage: it was solely her likeness that propelled the consistent use of the answer in the crossword^xi.