TX is in 2nd (~$1.3t) for US, way behind CA (~$1.9t, bigger than India) in 2010. Using same year, TX would be 13th between Mexico (~$1t) and Spain (~$1.4t). Some data-collectors combine European countries into one big "EU" blob, where TX would be in 10th place. (put TX one more place down if you include CA in those lists, too)
If it makes TX feel any better, they have a bigger economy by nominal GDP than New Zealand, Israel, Thailand, and Switzerland combined. Houston alone has a significantly higher GDP than Greece. In the US, when we think about CA's troubled economy and $.4t debt, it seems small and inconsequential (it's not very rare to be talked about where I am), but it's roughly the same amount of debt as Greece holds where a default is supposed to be catastrophic. Even the default by Detroit, the largely-irrelevant living dinosaur, was ~50% larger than Iceland's GDP in 2010.
Nations' GDP (2010) http://siteresources.worldbank.org/DATASTATISTICS/Resources/GDP.pdf
TX GDP (2010) http://www.usgovernmentrevenue.com/state_rev_summary.php?chart=Z0&year=2010&units=d&rank=a
Houston GDP http://greyhill.com/gross-metropolitan-product/
Other sources you can find for yourself
