Haven't been able to find much information about anything that happened between the January 1901 meeting and the July 1901 meeting.

Here's some more recent history:

Last year (February 200) after the major parties Iowa Caususes (January 2000) Socialist Party
presidential candidate David McReynolds toured Iowa.

In the election of 1900 the Socialist Party ticket of Eugene V. Debs for president and Job Harriman for vice-president received 97,730 votes.

At a convention held in January of 1901 the Social Democratic party agreed to meet in Indianapolis the following July for the purpose of unifying with the dissident faction of the Socialist Labor Party.

"With the question of unity settled, the major question before the July convention concerned the nature of the party's program. Specifically, the debate focused on whether to include such immediate demands as municipal ownership of untilities or election reforms as part of the Socialist program."
(from Eugene V. Debs: Citizen and Socialist by Nick Salvatore, University of Illinois Press, p. 189)

The Socialist Party of the United States of America was formally organized
at a unity convention in Indianapolis in 1901. The two merging groups were
the Social Democratic Party of Eugene Victor Debs and the "Kangaroo" wing
of the older Socialist Labor Party.

The SDP had been organized in 1898 by veterans of the
Pullman strike of the American Railway Union, led by Debs, and was largely
composed of American-born workers. The SLP had its roots in the American
circles of Marx's First International and the Workingmen's Party of America,
and was primarily composed of immigrants in big cities. By the 1880's,
under the rule of Daniel De Leon, it had become increasingly intolerant
of internal dissent and had suffered several splits.

From the beginning the Socialist Party was the ecumenical organization
for American radicals. Its membership included Marxists of various kinds,
Christian socialists, Zionist and anti-Zionist Jewish socialists, foreign-language
speaking sections, single-taxers and virtually every variety of American radical.
On the divisive issue of "reform vs. revolution" the Socialist Party from the beginning
adopted a compromise formula, producing platforms calling for revolutionary change
but also making "immediate demands" of a reformist nature. A perennially unresolved
issue was whether revolutionary change could come about without violence;
there were always pacifists and evolutionists in the Party as well as those
opposed to both those views. The Socialist Party historically stressed
cooperatives as much as labor unions, and included the concepts of revolution
by education and of "building the new society within the shell of the old."

(From the website of the Socialist Party-USA)