Caltrans warning sign for immigrants potentially entering and crossing the freeway. Designed by Caltrans graphic artist John Hood in the late 1980s and erected along San Diego freeways starting in September 1990, most notably near the border checkpoints at San Ysidro and Camp Pendleton. Numerous parodies have been derived from the original sign.
vectorisation: Own work, derived from file photographs and articles including:

Mydans, Seth. "One Last Deadly Crossing for Illegal Aliens". 7 January 1991. The New York Times. Accessed 15 June 2015.
Berestein, Leslie. "Highway safety sign becomes running story on immigration". 10 April 2005. San Diego Union-Tribune. Accessed 15 June 2015.
Gold, Scott. "The artist behind the iconic 'running immigrants' image". 4 April 2008. Los Angeles Times. Accessed 15 June 2015.
original: John Hood, Caltrans graphic artist  vectorisation: Mliu92