an executive order was passed by president roosevelt, which gave goethals complete authority to deport anyone not contributing productively to the construction project, so generally speaking workers found other ways besides strikes, except for those pesky spaniards. they struck and they rioted. they were causing trouble throughout the construction era, but that was the key exception. >> host: where they needed? >> guest: the spaniards? >> host: right. >> guest: the more they rioted and protested the less the government felt they were needed and by 1911, 1912, the u.s. government stopped bringing in spaniards and gradually let them go because they were finding that the spaniards were more trouble than they were worth. >> host: julie greene we are talking with professor julie greene at the university of maryland about her book "the canal builders" making america's empire. at the panama canal. you talked about the archives. where were the archives you found on the panama canal? >> guest: that was such a fun part of the project, discovering archival sources. the biggest single source for i