A runoff in the Dallas suburb of Frisco is testing whether anti-Muslim rhetoric, prominent in G.O.P. primaries this year, can win over a broader set of voters.

© Desiree Rios for The New York Times

Federal agents are there for security, not immigration enforcement, officials say. But trust is fragile after the administration’s recent crackdowns.

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Officials in North Texas will watch for potential threats from a new $40 million emergency operations center, one of many new security precautions in place across North America.

© Desiree Rios for The New York Times