“We left after that — a lot of us left after that,” she said, sitting at her kitchen table.

At Indiana University, she earned a master’s degree in statistics while working part time in a hospital. Now, Ms. Zhou lives in Clarksville, Md., with her husband, a software engineer who also emigrated from China, and their son and daughter.

She knocked on doors for a presidential candidate before she could even vote — in 2004 in Pennsylvania for John Kerry. She was angry about the war in Iraq. Her first vote after becoming a citizen in 2007 was for Barack Obama.

But never has she been more politically active than during the short life of the sanctuary bill in Howard County.

Ms. Zhou first learned of it on WeChat, a messaging app popular among Chinese-Americans. She talked to friends and neighbors. Nobody liked the idea. Many were afraid that carving out a safe space for illegal immigrants would mean that more would come, and that public-school classes would swell and teachers would be spread thin.

So on a cold night in early January, about a dozen people gathered around Ms. Zhou’s long wooden dining table, drafted short speeches and took turns delivering them over steaming bowls of sweet bean soup with chia seeds. Most, she said, had never done anything more political than vote.

“I read my draft, but then I totally changed it,” Ms. Zhou recalled. “I talked a lot about how many years it took to get citizenship, and I actually started crying. One person said, ‘Don’t do that!’ And someone else said, ‘Let her cry!’”

The bill’s supporters argued that, sanctuary or not, undocumented immigrants would be unable to afford housing in the county, where the typical home is valued at around $430,000.