While emo was withdrewn in the underground, The second wave occured. A lot of bands in this second wave formed in the mid-west of the USA. That's why this era is also called Midwest-emo. In these underground years, emo formed a national subculture. Emo fans idenficated themselves with these emo bands.

This midwest-emo started to let go the hardcore-punk cores more. It sounded less rough and more melodic than the first-wave emo. In this era, the indie rock (which wasn't that populair anymore) started to become part of this culture. Indie is short for independ, which means that these bands where independed from record labels and followed the punks Do-It-Yourself movement. According to the author and critic Andy Greenwald, this midwest emo peroid was the period were a lot (not al of them) of the stereotypical emo is comming from. Extreme emotional, glasses wearing, bands played by boys, School music.

Some also say that the Midwest-emo genre separates from the traditional emo genre and that these are 2 different music genres. While the normal emo is much darker and has more serious lyrics like about suicide or depression, Midwest-emo has more themes like relation problems or weed.

The midwest-emo clothing style is simulair to indie clothing.

A lot of midwest-emo bands did form like: The Get Up Kids, Sunny Day Real Estate, Cap n' Jazz and The Promise Ring. Because the midwest-emo sounded a lot friendlier, some record companies started to offer a contract to some Mid-west emo bands. A lot of these bands couldn't resist the offer. While other midwest-emo bands could stand against this offer and stayed faithfull to their indie labels. Because of the rise of populairity, a lot of emo bands started to withdraw from this genre and started to make other music. And again, emo pulled back to the underground...

Sources: Wikipedia, Wikipedia, Wikipedia, Aesthetics Wiki