National City, CA Sign Regulations: Digital Billboards (2026)

Two sections split the topic. Section 18.47.070 lists prohibited signs in all zones and at all times unless another provision explicitly authorizes them, and its first item is new billboards, conversion of existing billboards to digital or dynamic or tri-vision display, expansion of the display face of any existing billboard (except as authorized by state law), and the installation of an additional display face to an existing billboard structure. Under § 18.47.040, a billboard is a permanent sign structure that displays off-site commercial messages, offers its message area to sponsors other than the owner or operator, or stands as a principal or secondary use of the land.

Section 18.47.080(K) then regulates digital display signs that are not billboards. 'Digital display' covers LED, LCD, plasma, and projected images that can change automatically or by remote or computer control. These signs are allowed in industrial, commercial, and mixed-use districts with a sign permit, and the digital display must be part of a master sign program. Maximum height is the same as for a non-digital sign. On properties fronting arterial roadways the digital portion cannot exceed twenty-five percent of the allowable display area, and on highways it cannot exceed fifty percent. Only one sign using digital display is permitted per site. Images cannot move or appear to move, each still image must be on display a minimum of eight seconds, and transitions cannot exceed one second.

Each sign needs a photometric sensor adjusting intensity for daytime and nighttime viewing, and nighttime intensity is limited to 0.3 foot-candles over ambient levels as measured at a preset distance established by the Lewin Report prepared for the Outdoor Advertising Association of America. The city can modify or further restrict intensity if the lighting distracts drivers or affects nearby residential property. The display cannot operate between 10:00 p.m. and 7:00 a.m. Digital signs not attached to a building go on one support column only, and a wall-mounted digital sign cannot obscure windows or architectural features. No digital sign can sit within one mile of another on the same side of a highway, or within one thousand feet of another digital display on any street. Content is limited to noncommercial messages and onsite commercial messages, never general advertising for hire.