The Wisconsin State Patrol spent $5.7 million to protect Republican Gov. Scott Walker, First Lady Tonette Walker and Lt. Gov. Rebecca Kleefisch from 2011 through 2013.
The governor's office released records showing the patrol's Dignitary Protection Unit spent $1.6 million on security for the trio in 2011, $1.9 million in 2012 and $2.2 million in 2013.
For comparison, the unit spent $570,876 in 2009 and $657,457 in 2010 to protect Democratic Gov. Jim Doyle.
The unit didn't protect Lt. Gov Barbara Lawton during those years.
Walker spokeswoman Jocelyn Webster says in an email that the unit decided to include Kleefisch due to "the difference in circumstances."
Walker's first two years in office were marked by bitter protests against his plan to strip most public workers of nearly all their union rights.
Critics say the governor's expenses are higher because Walker, who may run for president in 2016, frequently travels.