Today marks the last day that Janet Napolitano will serve as Secretary of Homeland Security before she leaves for the University of California.
The last time Napolitano left a job -- when she gave up being Arizona's governor in order to head the Department of Homeland Security under Obama -- it shaped immigration policy not only on a national level, but also back in her home state due to her absence.
Aside from what Napolitano did at DHS on immigration - expanding the Secure Communities program to identify immigrants in local jails, creating the Deferred Action for Childhood Arrivals program, deporting record high numbers of immigrants -- there is what her departure from Arizona meant to that state.
Napolitano's departure triggered then-Secretary of State Jan Brewer to assume the Governor's post, which is partly what propelled Arizona immigration enforcement legislation, SB 1070, to become law.
Brewer championed the law, when it is almost certain Napolitano would have vetoed it.
The passage of the law has been a pivot point in the country's debate over immigration.
The chain of events is also deeply ironic: As Napolitano held the post of the country's top immigration enforcement officer, her decision to leave Arizona allowed state lawmakers to pass a law the U.S. Supreme Court would eventually rule had several sections that preempted the federal government's authority on immigration enforcement.
During Napolitano's tenure, one of the most high profile changes in immigration policy is arguably the Deferred Action for Childhood Arrivals program, known as DACA.
But one of the policy's most prominent challengers is none other than Napolitano's successor in Arizona, Governor Brewer.
On the day the policy - which allows young immigrants brought to the country illegally as children to get work permits and a reprieve from deportation - took effect, Brewer announced these immigrants would still be ineligible for state driver's licenses.
In response to a lawsuit challenging this Executive Order, Brewer's lawyers have argued the Obama administration's policy does not grant DACA recipients lawful presence because it was not approved by Congress.
The country is currently engaged in a critical debate over the future of immigration reform. In a few years, we may have a better sense of what the consequences of Napolitano leaving DHS at this moment will be.
