|Current Washington Nationals home jersey|
The first professional teams appeared in Washington D.C. (District of Columbia) in 1870. There was a team called the "Olympics" and another called the "Nationals". Other teams were known as the "Nationals" and other names that played off the city being the "Capital City," such as the "Statesmen" and "Senators." Those names have bounced back and forth in and out of D.C. over the years.
By the late 1800s, "Senators" was commonly used in the media as the name for the National League team and that name carried over to the new American League entry in 1901.
When new owners took over in 1905, they solicited fans and writers for a new nickname and they decided to bounce back to using "Nationals" which was what the shirts said in 1905 and 1906.
But their name was somewhat ambiguous and since writers frequently referred to individual major league teams as being "Americans" or "Nationals" (in reference to their league affiliation), you can find the Washington Nationals of the American League a confusing name and print references to the team as "Senators," "Nationals" (or even the "Nats") interchangeably.
According to Wikipedia, the 1933 programs for the games played in New York City advertised "Giants vs. Senators", while programs for the games played in Washington included a photo of Washington manager Joe Cronin with the caption "Nationals' Manager."
"Nationals" or "Nats" was still used on baseball cards issued by Topps as late as 1956, that name was falling out of fashion. (The popular 1955 Broadway musical Damn Yankees referred to the club as the "Senators.")
The Senators faced the heavily-favored New York Giants in the 1924 World Series and came away with the only World Series triumph for the franchise during their 60-year tenure in Washington.
|t-shirt with the old Washington Senators logo via amazon.com|
After the 1956 season, owner Calvin Griffith decided to officially change the name to Senators, but it wasn't until 1959 that the word "Senators" finally appeared on their shirts.
|Frank Howard, Washington Senators 1970 Topps card via amazon.com|
The Washington Senators was also the name of an NFL American football team that played from 1921 to 1922.
In the confusing world of team expansions and moves from city to city, in 1961, the Washington Senators moved to Minnesota and became the Minnesota Twins.
After the 1971 season, the new Senators moved to Arlington, Texas, and debuted as the Texas Rangers the following spring.
The current Washington Nationals team (now in the National League) was a transplanted team from Montreal in 2005, where they had been known as the Expos. The old Nationals name and "classic" headline abbreviation "Nats" was also revived. Actually, there was no possibility of using the old "Washington Senators" trademark as that is still owned by the Texas Rangers organization.