Charles Wagner wrote:

Every year I get a swath of this unpleasant weed across my lawn. In the
past I've picked it out, but it keeps coming back. Does anyone know what
it is and how to get rid of it?

http://www.charliewagner.net/Dscn0033.jpg
http://www.charliewagner.net/Dscn0034.jpg
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Regards, Charlie Wagner
http://www.charliewagner.com

Looks like crabgrass to me.

Checkout the following and click on the "crabgrass, common" link:

http://www.gardencountry.com/pages/weeds/weedchart.html