SR 702 is the Wharton Brook Connector, a short freeway (or long set of ramps) connecting US 5 to I-91 exit 13. Short-range plans in the early 1960s called for extending the freeway west to the Hartford Turnpike; longer-range plans even included a freeway roughly along Route 42, extending from Route 8 to Route 17. The Route 42 freeway never progressed beyond a dotted line on regional planning maps.

In the 1950s, the cities of Hamden and Wallingford (among others) were working out where the Relocated Route 5 freeway (today's I-91) should go. In 1956, the proposed line was an "Eastern Route" very similar to today's; but in the next few years, other alignments closer to downtown were considered, including a "Valley Route", near the Quinnipiac River, and a "Middle Route", between Elm and Main streets.

The Eastern Route, bypassing more developed areas, turned out to be the preferred alternative. There remained only the issue of how to move traffic from downtown to the new freeway. Center Street in Wallingford (Route 150) by itself would be overwhelmed. I-91 would need additional connector routes to US 5.

In November 1959, the state Highway Department announced it was recommending the Eastern Route for I-91, along with a connector passing by Wharton Brook state park to Toelle's Crossing at US 5.

By 1963, the design for the Wharton Brook Connector had matured. A planning map (shown in 1961) depicted four interchanges along the freeway:

• 3-level interchange at I-91
• partial cloverleaf at US 5 (across from railroad tracks)
• diamond interchange at a future cross street halfway along Toelles Road
• diamond interchange at Wilbur Cross Parkway. Here, SR 702 would have cross traffic; this is not a full freeway to freeway interchange

In 1963, three connector projects in Wallingford were under discussion:

• top priority: SR 702, from I-91 to an at-grade intersection with US 5; this opened with I-91 in 1966
• second priority: Route 68, from US 5 to I-91; this was also built, a few years later
• third priority: extend SR 702 west to Hartford Turnpike, with an interchange at US 5 (and possibly with Route 15). This was never built.

In 1969, as part of a $250 million statewide plan, $1.5 million was included for engineering and land acquisition for the connector. The state engaged a design firm to plan the project in 1970.

In 1974, legislators considered diverting funds from a Route 68 project to help complete an SR 702 extension to the Hartford Turnpike by the target date of 1978.

In 1975, the state estimated it would cost $9 million to extend the route 0.7 miles west to the Hartford Turnpike, just beyond Route 15. I don't know if an interchange was planned at Route 15, also known as the Wilbur Cross Parkway; a similar connector highway, Route 40, crosses the Parkway to the south with no access at all.

I haven't found any plans later than 1975 to extend SR 702.

Its western terminus had been notorious as one of the most dangerous intersections in Wallingford; in 2010, the state widened US 5 and added turning lanes to mitigate problems there.