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Iowa/Major roads/Main

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===== Naming =====
Primary streets should only be named the actual name of the street (same name as house numbering indicates). The only exceptions to this rule would be tricky intersections where a county road sign is the only prevalent name of the street.
===== County Roads In Iowa =====
Iowa adopted its present county road numbering system in the late 1960's, featuring alphanumeric route numbers on the blue pentagon signs that are also used in many other states. Before that, county roads were given single-letter or double-letter designations, much like Wisconsin's county trunk roads and Missouri's state supplementary roads.
*East-west county roads start with "A" in the northern part of the state and ascend alphabetically until reaching "J" in the south. Example: Johnson County Road F46.
*North-south county roads start with "K" in the western part of the state and run all the way through "Z" in the south. Example: Scott County Road Y40.
*Diagonal county roads use letter-number-letter route designations instead of the usual letter-and-two number route; the letters used correspond to the letters of other county roads in that area. Examples: Linn County Road W6E, Clayton County Road C9Y. A few four digit county roads exist, though, including Lyon/Sioux County Road A54B, Delaware County Road C60X, Jackson County Road E23Y, and Louisa County Road G44X.
*Four letters — I, O, Q, and U — are not used in route numbering. ("I" may be too similar to the number "1," plus Interstate highways are also referred to as "I-xx" routes. "O" and "Q" are too similar to "0" (zero), and "U" is too close to "V.")
Letters tend to change about every 20 to 25 linear miles; they usually do not change with county lines (except for the horizontal roads in western Iowa).
*Numbers generally run from 10 through 80, ascending from west to east and north to south.
*Numbers can be duplicated in multiple counties on multiple discontinuous routes.
*Cardinal direction markers are seldom used, since the first letter should tell you whether it is an east-west or north-south route.
*County roads are usually not signed in the city limits of larger cities, as the city usually takes over jurisdiction of the road at that point. Example: County Road W66 runs along Dubuque Street north of Iowa City and Gilbert Street south of there, but it is not signed in the city limits.