As has been said, the Americans did absolutely engage in Empire making; as with most everybody, they went along the route of least resistance, out on the West and through Native and Mexican-held areas. Those were seized, colonized, and an accompanying imperialist creed emerged in the form of Manifest Destiny.
By the time that was resolved and the USA could start looking outwards for non-contiguous gains, however, the problem of Slavery became central and made any further attempt (the Golden Circle idea, the Liberian outlet) a poisoned apple - because they would have given the slavers more power. So they mostly stayed moot, as the Civil War developed, erupted, had consequences.
By the time the USA had resolved internal problems well enough to return caring outwards, most of the world was either recognized as independent or colonized by European powers.
With Eastern opportunities reduced to zero, the Americans moved towards estabilishing themselves in LatAm; which could not easily be directly invaded and controlled, not to mention inhabited by most unwelcome (for the WASP ruling class) Latino Catholics. Thus, plans for economic control were enacted; territorial acquisition opportunities remained in the Pacific, but even then, they were mostly island bases, with the only major exception - the Philippines - happening through a combination of factors rather than deliberate intent to obtain a large colony.
The USA's early expansion gave them such a plenty of surplus land and resources, it satisfied industrial and demographic needs that instead forced the European to fight, sail and colonize for a whole century.