Indiana State Road
| State Roads in Indiana | |
|---|---|
  
State Road markers
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| Highway names | |
| Interstates: | Interstate X (I-X) |
| US Highways: | U.S. Highway X (US X) |
| State: | State Road X (SR X) |
| System links | |
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State Roads in the U.S. state of Indiana are numbered rationally: in general, odd one-digit and two-digit highways are north–south highways, numbers increasing toward the west; even one-digit and two-digit highways are east-west highways, numbers increasing toward the south, the opposite of the Interstate Highway System. Three-digit highways are related, as a rule, to the single-digit or two-digit parent US or State Road; thus State Road 205 (SR 205) is related to SR 5, and SR 120 is related to U.S. Highway 20 (US 20).
Exceptions to this system are SR 37, SR 47, SR 56, SR 57, SR 62, and SR 67, diagonal routes, the defunct SR 100 beltline around Indianapolis, SR 135 (which acts like a two-digit state highway), and both SR 149 and SR 249 (which are arterials between SR 49 and SR 51). Another exception to the system is SR 265; this highway is a two-mile-long (3.2 km) extension that exists between Interstate 265 (I-265) and I-65 and is over 100 miles (160 km) east of either SR 65 or SR 165, both located in Southwestern Indiana near Evansville.
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