First was by Baldwin, 1886, 30" gauge 2-4-2 for the Antofagasta Railway (Chile).
Oahu Railway purchased 5 Baldwin outside-frame locomotives in 1897, first was an 0-6-0, don't know about the rest.
First domestic 3' ga. outside frame, two 2-8-0's to Crystal River RR in 1900. These eventually became D&RGW's 360 - 361.
Source: Hilton, American NG RR's
regards,
Jeff