Pettersen was first elected to represent House District 28 in the 2012 election. She has lived in Jefferson County for almost her whole life and was the first member of her family to graduate from college. Before running for State Representative she worked for New Era Colorado, which is a non-profit whose mission is to increase youth participation in politics and the government process. In the 2014 legislative session, Pettersen sponsored legislation to assist Colorado's students and families. One bill would help low- and middle-income students receive more tuition assistance and provide more support to students so they can complete their degree. Two other bills help families making less than $25,000 a year find affordable child care and give counties in the state more flexibility to help parents stay in the workforce. During the 2013 session, Pettersen sponsored a bill cutting red-tape to make it easier for Coloradans to put their income tax returns into a college savings account. She also sponsored a bill that allows someone who dropped out of high school to complete their high school education at a junior or community college. In 2017, Petterson married Ian Silverii, the executive director of ProgressNow Colorado, at the Colorado Governor's Mansion.
2013 legislative session
In 2013, Pettersen opposed a repeal of the death penalty in Colorado. Pettersen sponsored legislation making it easier for taxpayers to put their income tax returns into a college savings account as well as legislation allowing someone who dropped out of high school to finish their education requirements at a community or junior college.
2014 legislative session
Pettersen passed legislation to help more Colorado students get a college education by providing more tuition assistance to low- and middle-income Colorado families. She also sponsored legislation to help struggling families find affordable childcare so that parents can remain in their jobs and continue to pursue their careers.
2018 congressional election
On April 9, 2017, following Ed Perlmutter's announcement that he was running for Governor of Colorado rather than reelection in 2018, Pettersen announced her candidacy for Colorado's 7th congressional district seat. However, after Ed Perlmutter's announcement to reenter the congressional race she ended her campaign.
2019 recall effort
In July, 2019, the Colorado Secretary of State approved the circulation of a recall petition against Petterson. The organizers of the recall had until September 16, 2019 to gather 18,376 signatures to put the recall question on the ballot, but on September 10 they announced that they were abandoning the recall effort and not turning in any signatures. The recall petition stated that Petterson should be recalled because she supports taxpayer-funded heroin-injection sites, and because she supported SB 19-042, SB 19-181, HB 19-1032, and HB 19-1177.
