What’s been in effect ever since (with the brief exception of 1914-15, when the Federal League operated) is a two-major-league system in baseball. What may have also prevailed ever since is a sense that the two leagues, American and National, have represented essentially equal and similar brands. This may not be a valid perception.
In fact, the two leagues, while generally presenting equivalent styles and qualities of play over the decades, have often differed quite a bit. In two parts, we’ll compare and contrast the AL and NL in their century of companionship.
1901-1919: A Great Start for the Junior Circuit
In their first two decades of co-existence, the two leagues presented similar products in terms of style. Run scoring levels between the leagues were consistently within 10% of each other, with neither league sustaining a period of scoring superiority.
There was no significant difference between the leagues in batting average. The National League consistently featured more home runs (probably mostly due to the effect of Baker Bowl in Philadelphia), but in that era home runs were such an overall rarity that the NL’s advantage didn’t yield a difference in scoring, especially since the AL, increasingly through the 1910s, tended to have higher walk rates. Stolen base rates were at all-time highs in both leagues, and while there were generally slightly more in the AL, the differences weren’t dramatic — generally only a few percentage points of distinction between the leagues.
But while the leagues were rather indistinguishable in style of play, they weren’t equal at the turnstile: almost from the start, the upstart American League was better-attended than the Senior Circuit. NL attendance per game exceeded that of the AL in 1901 and 1903, but then never again for the entire period.
The attendance advantage of the AL wasn’t always dramatic — generally within 10-15% of the NL (with one anomaly in the Federal League’s initial season of 1914, when National League attendance took a sharp dip). But in the last three years of the period (1917-19) the AL’s attendance superiority assumed a more significant posture, with successive seasons of 22%, 24%, and 27% dominance over the NL.
Why this was so is an interesting question. Both leagues shared the major city markets (New York, Chicago, Philadelphia, Boston, St. Louis); indeed the NL had two franchises in New York City. A systemic market-based explanation for the AL’s attendance advantage doesn’t suggest itself. More likely the primary reason for the AL’s greater popularity is simply of function of the quality of the product: the American League probably presented a generally superior level of play in those decades.
Think of the very greatest players, the first-tier Hall of Fame-quality talent of that era: Honus Wagner, Christy Mathewson, and Grover Cleveland Alexander were in the NL. But the AL featured Cy Young, Nap Lajoie, Ty Cobb, Walter Johnson, Tris Speaker, Eddie Collins, and Joe Jackson. Counting superstars is a less-than-scientific method of comparing league quality, but it does seem to be the case that the very best players in (white) baseball in the 1901-1919 era tended to be in the AL. Couple this with the Junior Loop’s near-total superiority in attendance, and it’s a fair inference that fans preferred the American League product because it was generally just better.
Oh, yeah. There was one other young star who emerged in the American League toward the end of the period … a southpaw pitcher. The kid could hit a little, too. Already a superstar in 1915-19, he would take the sport by storm in 1920, coming to New York and leading a transformation into a new mode of play.
1920-30: Balance in the Jazz Age
The cork-centered “live” ball had been introduced to the major leagues long before 1920 — in 1911, to be exact. Hitting and scoring in both leagues took a dramatic jump in 1911-12. But pitchers soon learned to counteract the livelier new ball by perfecting, ever more ardently, methods to deface and defile it: spitballs, tobacco balls, coffee balls, mudballs; baseballs scratched and torn and stained and altered to such a degree that they became easier to curve and more difficult to see and hit. Scoring levels in both leagues declined after 1912, and for the rest of the decade they were nearly as low as they had been before 1911.
In 1920, both leagues adopted a new rule: pitchers were no longer allowed to deface the ball (under a grandfather clause, a few career spitballers were allowed to continue to ply their trade). As a means of enforcing the rule, a fresh, new, clean white baseball would be inserted into the game whenever the current ball became stained or scratched.
The rule change was made primarily in the interest of keeping the ball sanitary — getting rid of those brown slimy horrors — but the impact on scoring was unanticipated and enormous. With a fresh, new, clean, white, live cork-centered baseball in play at all times, batters suddenly entered the promised land.
Babe Ruth led the way, of course. But tremendous as his impact was, he was not the only hitter who enjoyed huge and immediate success in the new conditions. Hitting and scoring soared in 1920, 1921, and 1922, at a rate of increase never seen before or since.
The effect was pretty even across both leagues: once stabilized in the new circumstances, neither league outscored the other by as much as 10% in any season between 1922 and 1930. The leagues presented remarkably equal batting averages, strikeout rates, and stolen base rates across the decade. The differences between the leagues that had been apparent earlier — the NL featuring more home runs, the AL featuring more bases on balls — continued, though not as dramatically as before, and indeed by the end of the 1920s the walk rate difference had disappeared.
Even in terms of attendance, the 1920-30 period is one of great balance between the two leagues. Babe Ruth notwithstanding, the AL superiority in attendance disappeared in the ’20s. By 1926, the leagues were almost exactly even in attendance, and from 1927 through 1930 the NL was better attended — essentially for the first time in the 20th century — by rates of 5% to 15%.
Why the shift in the attendance trend? Performing the superstar count for the era reveals a roughly equivalent strength in “name brands”: along with the aging stars Johnson, Cobb, and Speaker, there was Ruth, George Sisler, Harry Heilmann, Lou Gehrig, Al Simmons, and the emerging Lefty Grove in the American League. But the NL countered with the aging star Alexander, plus Rogers Hornsby, Frankie Frisch, Dazzy Vance, Paul Waner, Hack Wilson, Pie Traynor, and the emerging Mel Ott. Perhaps the talent advantage that the AL had enjoyed was no longer there by the late 1920s.
1931-42: Keep Your Eye On the Ball
The 1920s had featured higher and higher scoring, and the 1930 season was the highest, with record-setting levels in both leagues. Suddenly in 1931, things changed — but only in the National League.
In the American League, scoring continued along its merry way throughout the 1930s, consistently exceeding 1920s levels. In 1936 the AL posted the highest-scoring season in its history. Often, today, the 1930s are referred to as an extremely high-scoring era, and this is true — for the American League.
But the 1930s National League was quite a different story. Run scoring in the NL in 1931 dropped by 1.2 runs per team per game, the largest single-season decline in major league history, taking the NL back down to a scoring level it hadn’t seen since 1920. In every year from 1931 through 1942, the American League outscored the National. Never was the difference in scoring less than 8%, and it was as much as 26%. Among the 15 greatest scoring difference seasons between the leagues in history, eight occurred between 1931 and 1942:
YEAR DIFF RANK 1933 26% 1st 1938 22% 3rd 1936 20% 4th 1939 17% 6th 1937 16% 8th 1931 15% 11th 1932 14% 13th 1940 13% 14th
What explains this? How could the leagues suddenly go from being consistently equivalent as scoring environments through 1930, to dramatically and persistently different scoring environments from 1931 through 1942? The NL didn’t suddenly adopt new, pitcher-friendly ballparks in 1931. Neither league adopted any significant playing rule changes in 1931. Great hitters didn’t suddenly get traded from the NL to the AL in exchange for great pitchers.
I think there’s only one possible explanation: the baseball. Each league in those days authorized and used its own private-label baseball; there was no such thing as a single standard “major league” ball. Given the evidence, I don’t think there’s any possible conclusion to draw but this: whether intentionally or not, the National League used a distinctly less lively baseball than the American League from 1931 through 1942.
Neither league, as far as I know, ever clearly acknowledged this, although I’ve read many oblique references and rumors regarding it over the years. The closest thing my (admittedly not very thorough) research has been able to find is this “Editorial Comment” by John B. Foster which opens the 1934 Spalding Official Base Ball Guide (in 1933 NL scoring had dropped to its lowest level since pre-1920, and the difference in scoring between the leagues was the greatest in history):
…under the platform of separate balls for the two big leagues, made in such a manner as to create heavier batting for one as opposed to the other, there was no question about the batting. It was then attributed to the slightly different method employed in the manufacture of the ball, which was sensible enough, since the National League openly avowed that its ball was slightly slower than that used by the American League, and consequently its batters could not be expected to do quite as much execution with it.
The difference between the ball used by the National League and that which was in use in the American League was in the manner of sewing and in the cover, which was slightly heavier in the National League…
Now all this has been abolished and done away with. The ball that will be used in the American League will be of the same construction as that employed by the National League, and the players of one organization will not have the slightest advantage over those of the other.
What the evidence suggests really happened, I think, is that the NL agreed to liven up its extraordinarily “dead” 1933 ball, but that the leagues didn’t truly adopt standardized baseball specs until World War II forced them to — which we’ll get into shortly.
But this is something very important to keep in mind when assessing players of the 1931-42 era. We may tend to see the best hitters of that time as being in the AL (Gehrig, Foxx, Greenberg, etc.), with the NL’s best hitters (Ott, Klein, Medwick, etc.) as not quite measuring up. Maybe the best hitters were American Leaguers, but a careful scoring-environment context assessment needs to be applied in order to be certain.
Looking at attendance in the 1931-42 period reveals something interesting as well: even though the AL featured a distinctly more action-packed brand of play, the AL was not a more popular product. Attendance between the leagues was remarkably equivalent: in the 12 seasons, the AL had higher attendance six times, and the NL also six. It seems fair to conclude that even though fans obviously comprehended the two leagues as presenting different styles, neither style was generally more popular than the other. Nor, as revealed by their attending habits, did fans perceive either league as presenting a higher quality of play.
The 1931-42 period stands, therefore, as one of the most interesting in history: the two leagues were providing extraordinarily different styles of product, each of which was equally valued by customers.
1943-1955: Sowing the Seeds of Change
In 1943 National League scoring matched American League scoring for the first time since 1930. This happened not because the NL increased its slugging, but because the AL finally dropped down to the NL’s lower-scoring mode. The explanation, again, may clearly be found in the baseball itself.
World War II raw material restrictions were fully in effect by 1943, and both leagues were forced to adopt a baseball constructed with inferior components. Derisively nicknamed the “balata ball,” despite various methods employed, the wartime ball was distinctly non-lively; home runs and scoring plunged in both leagues to levels not seen since before 1920. Whether they preferred it or not, neither league could maintain exclusive control over the specs of its ball for the duration of the war.
Beginning in 1946, however, such restrictions were removed. While it took a year or two for scoring to rebound all the way to pre-war levels, it’s clear that the “balata ball” was discarded: home runs increased in 1946 and began a long upward climb. But what’s striking is the degree to which, as scoring increased in the late 1940s, it did so in both leagues.
The clear distinction between the AL and NL that had prevailed in 1931-42 didn’t reassert itself: in the 10 seasons from 1946 through 1955, the AL outscored the NL five times, the NL outscored the AL four times, and in one year they were exactly equal. In no season in that period did either league outscore the other by more than 10%.
The only conclusion one can draw from this is that, after World War II, at least, John B. Foster’s 1934 pronouncement was finally true: “The ball that will be used in the American League will be of the same construction as that employed by the National League.”
Beneath similarities in overall scoring levels, however, there were some remarkable differences between the leagues in 1946-55. The NL resumed the superiority in home run rates that it had held until the 1930s. The AL consistently featured more walks, though not as many more as had prevailed in the ’30s. The NL generally had a few more stolen bases, though its stolen base advantage was not as great as that which the AL had shown in most of the seasons in the ’30s and early ’40s.
But the most striking difference between the leagues in 1946-55 was, of course, the degree to which the leagues racially integrated at very different rates. It wasn’t just that Jackie Robinson was in the NL a few months before Larry Doby was in the AL; through the entire period, players of color began to be deployed much more readily by NL teams than by AL teams. While in 1955, only two AL teams (the Tigers and Red Sox) remained all-white, as opposed to one in the NL (the Phillies), the different levels of integration go much deeper than that.
Players of color used in significant roles in the AL in 1955 were Larry Doby, Elston Howard, Connie Johnson, Hector Lopez, Minnie Minoso, Carlos Paula, Dave Pope, Vic Power, Harry Simpson, and Al Smith: 10 players, several of them stars, one who would be elected to the Hall of Fame.
In the NL in 1955 were Hank Aaron, Sandy Amoros, Gene Baker, Ernie Banks, Bill Bruton, Roy Campanella, Roberto Clemente, George Crowe, Lino Donoso, Jim Gilliam, Ruben Gomez, Chuck Harmon, Monte Irvin, Sam Jones, Brooks Lawrence, Willie Mays, Roman Mejias, Don Newcombe, Jackie Robinson, Hank Thompson, and Bob Thurman: 21 players, many of them stars, seven who would become Hall of Famers.
The very different level of introduction of black talent into the two leagues would continue in the years following 1955, and would inevitably lead to different levels of quality of play between the two leagues: it was entirely impossible for the AL to offset, in deployment of greater white talent (which it didn’t do anyway), the huge talent advantage it ceded to the NL in black talent.
While the AL tended to have better attendance than the NL in the 1946-55 period (leading the NL in seven of the 10 seasons), the growing advantage in quality of players that the NL was accumulating would soon change that. The period following 1955 would see the greatest attendance disparities between the leagues in history, a situation which would bring the AL to a state of crisis by the early 1970s.
Coming next time: A Tale of Two Leagues (Part Two: 1956-2003).
References & Resources
The league statistics used for this article were taken from the baseball-reference.com league pages: http://www.baseball-reference.com/leagues/AL.shtml and http://www.baseball-reference.com/leagues/NL.shtml.
I’ve incorporated all this data and performed a fair amount of comparative analyses of it on an Excel spreadsheet. I’d be happy to share the spreadsheet with anyone who wants a copy; just email me at
I also highly recommend the following website for graphical presentations of the stats of both leagues over the years: http://home.istar.ca/~mbein/baseball.html
An excellent source of information on players of color in the major leagues in the 1947-59 period is Moffi and Kronstadt's Crossing the Line: Black Major Leaguers, 1947-1959.