It is baseball season in the United States. Baseball is still known as America's national pastime despite competition from other professional sports and the game's evolution into more of an international sport.

The origins of baseball are centered in the northeastern United States. The first official game under modern rules was played at the Elysian Fields in Hoboken, New Jersey in 1846. The man who wrote the rules was Alexander Cartwright, who was part of the first official team, the New York Knickerbockers.

During the Civil War in the 1860s, baseball became an increasingly popular sport among Union soldiers. Frank Ceresi is a baseball historian. "This [photograph] is from the Civil War period and this takes place in the 37th Massachusetts volunteer army from during the Civil War."

Baseball's popularity grew after the Civil War. It attracted donors who wanted to sponsor teams.

In 1869, the Cincinnati Red Stockings became the first fully professional team. From there, more amateur teams turned pro. This was the beginning of what is now Major League Baseball.

Today, baseball is enjoyed by many Americans for many reasons.

"If you think of the story, it's woven in our culture",he said. "It hits on everything - civil rights, history, heroes, the great outdoors, competitions, all of those things are embodied in a game in our culture, and that's why it's so popular."

Baseball impacted the social fabric of America in the mid-20th century. At a time when much of the United States was heavily segregated, Jackie Robinson broke the color barrier in 1947, playing for the Brooklyn Dodgers as the first African-American in the major leagues.

Many others followed, but the process moved slowly, with the final team - the Boston Red Sox - only integrating in 1959.

Bob Dupuy, President of Major League Baseball, says the next wave of players was from outside the country.

"We are now 23 percent of our major league roaster are players that were born outside the United States",he said. "The predominant number of  the players are Latinos".

Though there's more diversity among the players, Ceresi said, part of the team still are not full equality in management or in ownership of the game.

While several countries enjoy thriving baseball leagues, the international record for baseball is mixed. This year's inaugural World Baseball Classic, which included Japan, China, South Korea, Australia and several Caribbean countries, was viewed by many as a success. However, the International Olympic Committee announced last year that it was dropping baseball from its list of sports after the 2008 Summer Games.