State Route 503 is a north–south state highway

State highway

State highway, state road or state route can refer to one of three related concepts, two of them related to a state or provincial government in a country that is divided into states or provinces :#A...

 in the southwestern quadrant of the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Ohio

Ohio

Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

. The southern terminus of SR 503 is at U.S. Route 127 (US 127) in Seven Mile

Seven Mile, Ohio

Seven Mile is a village in Butler County, Ohio, United States. The population was 678 at the 2000 census. The name of Seven Mile appears to be its location seven miles north of Hamilton, Ohio...

. Its northern terminus is at a T-intersection with SR 121

Ohio State Route 121

Ohio State Route 121 is a State Route in Western Ohio. It connects the cities of Versailles and Greenville to Richmond, Indiana. It is a north–south route for most of its existence, except the southern portion between Indiana and New Paris...

 on the eastern limits of the village

Village

A village is a clustered human settlement or community, larger than a hamlet with the population ranging from a few hundred to a few thousand , Though often located in rural areas, the term urban village is also applied to certain urban neighbourhoods, such as the West Village in Manhattan, New...

 of Wayne Lakes

Wayne Lakes, Ohio

Wayne Lakes is a village in Darke County, Ohio, United States. The population was 684 at the 2000 census.-Geography:Wayne Lakes is located at ....

.

Route description

Along its way, SR 503 travels through northern Butler County

Butler County, Ohio

Butler County is a county located in the state of Ohio, United States. As of 2010, the population was 368,130. Its county seat is Hamilton. It is named for General Richard Butler, who died in 1791 fighting Indians in northern Ohio. Butler's army marched out of Fort Hamilton, where the city of...

, eastern Preble County

Preble County, Ohio

As of the census of 2000, there were 42,337 people, 16,001 households, and 12,144 families residing in the county. The population density was 100 people per square mile . There were 17,186 housing units at an average density of 40 per square mile...

 and southern Darke County

Darke County, Ohio

As of the census of 2000, there were 53,309 people, 20,419 households, and 14,905 families residing in the county. The population density was 89 people per square mile . There were 21,583 housing units at an average density of 36 per square mile...

. There are no segments of SR 503 that are included as a part of the National Highway System

National Highway System (United States)

The National Highway System is a network of strategic highways within the United States, including the Interstate Highway System and other roads serving major airports, ports, rail or truck terminals, railway stations, pipeline terminals and other strategic transport facilities.Individual states...

, a network of highways identified as being most important for the economy, mobility and defense of the nation.

History

The SR 503 designation was assigned in 1937. The highway was established along the routing that it maintains to this day between US 127 in Seven Mile and SR 121 in Wayne Lakes. No changes of major significance have taken place to the routing of the highway since its inception.

Major intersections