what is the baseball "modern era"

[jdl22]

On Sportscenter after the RJ perfect game they gave some fact and said that this was the only perfect game of whatever type in the modern era.

What years define the modern era? Is it since the DH rule?

[Six_of_One]

I believe it means since 1900.

[andyfox]

It usually means since 1901, when the American League came into existence.

The National League started in 1876.